AU651653B2

AU651653B2 - Yieldable roof support system

Info

Publication number: AU651653B2
Application number: AU10083/92A
Authority: AU
Inventors: Ray Brandon; Thomas Herbst; Khaled Shawwaf; Johann Wlodkowski
Original assignee: Dyckerhoff and Widmann AG
Current assignee: Walter Bau AG
Priority date: 1991-01-22
Filing date: 1992-01-07
Publication date: 1994-07-28
Anticipated expiration: 2012-01-07
Also published as: GB9200725D0; PL293251A1; ZA92159B; AU1008392A; FR2671829A1; GB2252114A; CA2059575A1

Description

AUSTRALIA

Patents Act 6 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: So Dyckerhoff Widmann Aktiengesellschaft 0o a *o Actual Inventor(s): Si, Khaled Shawwaf Sto* Johann Wlodkowski ,r0* Thomas Herbst S Ray Brandon 0 Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street *o Melbourne 3000 AUSTRALIA S0o Invention Title: YIELDABLE ROOF SUPPORT SYSTEM 0 0 Our Ref 240754 POF Code: 1330/18411 I 0 The following statement is a full description of this invention, including I" the best method of performing it known to applicant(s): 1 6006 L L i -I I PATENT APPLICATION 30055 l- YIELDABLE ROOF SUPPORT SYSTEM Technical Field The present invention relates generally to supports, and more particularly to a support that yields in a controlled fashion in response to an applied load.

Background Art There is a need in mining operations, particularly in longwall mines, for a roof support that yields in a controlled fashion in response to 15 So roof loads. In the past, mine operators have used post-type roof supports in the form of wood timbers and cribbing. The timbers absorb the initial roof *oOO.o load and the cribbing yields as load is applied thereto so that catastrophic failure of the roof a aoao support is prevented. This type of roof support system is one attempt to approximate an ideal system which would be very stiff to handle the 0o00 initial load and yet have the ability to yield in a controlled fashion. However, timbers and cribbing 25 0 2 opresent a fire hazard, are expensive and are labor intensive. Also, timbers and cribbing occupy a relatively large volume of space and can thus interfere with ventilation and complicate movement 3 of materials and personnel into and out of a mine.

30 0 A yieldable steel post for use in supporting a roof of a mine is disclosed in Coal Magazine, June 1990, pages 136 and 137. The post includes a PATENT APPLICATION 30055 2 bottom leg telescoped within an upper leg wherein each leg comprises a length of pipe. A tapered expansion ring is welded on the lower leg at a desired position and bottom and top plates are welded to the lower and upper legs and are adapted to engage a floor and a roof, respectively, of a mine. As a compressive load is applied to the post, the expansion ring radially deforms the upper leg outwardly as the top leg moves relative to the 00 010 0 bottom leg.

0 A prior art yieldable roof support utilizes an upper slotted leg of hollow pipe tele- 0 scoped within a lower leg also of hollow pipe. A wedge is driven into the slot in the upper leg at a desired position. The wedge causes the upper leg to have an interference fit with the lower leg at this position. As load is applied to the support, 00 0 the lower leg is radially deformed by the upper 0 section of leg at the location of the wedge.

000 20 A further type of yieldable post is sold by Jennmar Corp. of Pittsburgh, Pennsylvania. This type of roof support includes an upper channel nested within a lower channel and one or more clamps that couple the upper and lower channels together.

Other types of roof supports include concrete donuts or cribbing and are described in an article appearing in Coal Age, March 1987, pages 30-33.

None of the foregoing post-type roof supports has been found to be entirely satisfactory in terms of expense, ease of manufacture and assembly and support capability.

M it AI'E4rf APPLICATION 30055 3 In addition to post-type supports, anchortype yieldable roof supports for tunnels and the like have been designed wherein a supporting rod extending through the surface of the rock into the tunnel includes a deformation member carried on one end of the rod in axial alignment with a steel tube. When the rod is placed in tension, the deformation member is deflected within the steel tube, thereby deforming the tube radially outwardly and permitting limited movement of the rod. Such a design is shown in Austrian Patent 378,823.

West German published patent specification 33 14 858 Al discloses a yieldable roof support including a rod having a series of stepped portions 15 "oo separated by tapered portions on one end thereof disposed within a steel tube. The stepped and tapered sections deform the steel tube radially o *too outwardly when the rod is placed in tension.

o 0 20 2 Summary of the Invention A yieldable support for a compressive load is capable of deflecting in a controlled fashio s a load is applied thereto and is readily adaptable o to many different load conditions.

More particularly, a s ,port comprises a base member having an open &e and a hollow interi- Sor, a forcing member h ing threads thereon and an end extending th ogh the open end of the base member into e hollow interior thereof and means 30 30 capable. f engaging the threads of the forcing meb r at an adjustable position for providing an interfering relationship between the base and forc- I L- According to one aspect of this invention there is provided a structure for supporting a compressive load, said structure including: a base member having an open end and a hollow interior; a force transferring member having an end extending through the open end of the base member into the hollow interior thereof and having threads thereon; and a tapered mandrel having a threaded bore therethrough for threaded engagement with said force transferring member, said mandrel being adjustable in position with respect to said force transferring member to enable height adjustment of said structure and being arranged for interference engagement with said base member upon application of a compressive load between said base member and said force transferring member.

According to another aspect of this invention there is provided a roof support for a mine, comprising: a pipe having first and second ends and walls defining a channel therethrough of circular cross-section having a substantially constant diameter over its length.

a bar having first and second ends and threads about an outer periphery thereof; a mandrel having a threaded bore therethrough in 00 engagement with the threads on the bar whereby the mandrel may be positioned at a desired point on the bar by turning the mandrel relative to the bar, the mandrel further including an outer surface of first diameter smaller than 0 0B the substantially constant diameter at a first end thereof and of second diameter larger than the substantially constant diameter at a second end thereof opposite the o00 first end; 04t 0. awherein the first end of the bar extends through the o first end of the pipe and the mandrel is disposed at least p partially within the pipe channel such that the outer 0o 35 surface thereof is in interferring contact with the walls of the pipe; and top and bottom plates disposed on the second ends of the bar and pipe, respectively, and adapted to engage a qPIiv roof and a floor, respectively, of a mine.

3ai .?AiiNT APPLICATION 30055 4 ing members as a compressive load is applied to.

Preferably, accordu o-C one aspect of the present invention, providing means comprises a tapered mre having a threaded bore therethrough Jn ngagement with the threads on the forcing mombos. Also preferably, the mandrel and the base member are circular in cross-section, the base member has an inner diameter of a first size throughout its length and the mandrel has an outer diameter of a second size less than the first size at one end thereof and a third size greater than the first size at another end thereof. Further in accordance with the preferred embodiment, the outer diameter of the mandrel increases linearly from the second size to the third size over a portion of its :2 length.

r" If desired, means may be carried by the forcing member and disposed within the base member 20 for centering the forcing member as relative movement occurs between the members in response to application of load thereto. In accordance with this aspect of the present invention, the centering 0° means preferably comprises a cylindrical nut dis- 25 posed on the ends of the forcing member.

0 0 Still further in accordance with this aspect of the present invention, the forcing member preferably comprises a threaded bar and the base member comprises a pipe which is radially expanded 30 o 30 by the forcing member during relative movement of the members.

i Li I I AL. AP:?LjAL'ION 30055 5 In accordance with a further aspect of th present invention, the providing means comprise a sliding nut and the base member has an inner diameter of a first size and the sliding nut as an outer diameter of a second size larger an the first size. Preferably, the sliding nut ncludes a bore therethrough having threads in eng gement with the forcing member threads wherein the forcing member threads have a first shear rength and the bore threads have a second shear /strength greater than the first shear strength so that the bore threads shear off the forci member threads as load is applied to the membe s.

Preferably, means/are carried by the forc- 5 ing member and disposed ithin the base member for o o centering the forcing ember as relative movement 0o O o. a occurs between the m mbers in response to applica- 0. tion of load the to. In accordance with this aspect of the p esent invention, the sliding nut 20 0 and the end of the base member are complementarily shaped to as ist in centering of the forcing member.

urther, means may be provided for limitting re tive movement of the members wherein the 25 ooo 2 limitf g means comprises a nut carried by the forca ing ember.

The support of the present invention is simple in design and effective to yieldably support compressive loads. Also, the length thereof may be o 30 easily adjusted so that mine roofs of differing heights can be accommodated.

I L ar L'iCATION 30055 6 Brief Description of the Drawings Figure 1 comprises an elevational view, partly in section, of a support according to the present invention before application of load thereto; Figure 2 comprises a view similar to Figure 1 of the support of the present invention after application of load thereto; Figure 3 comprises a sectional view of the base member of Figures 1 and 2; Figure 4 comprises a plan view of the base member; Figure 5 comprises a sectional view of the top plate of Figures 1 and 2; Figure 6 comprises a bottom view of the top plate of Figure 7; Figure 7 comprises a partial sectional view of the mandrel of Figures 1 and 2; Figure 8 comprises a plan view of the 20 mandrel; Figure 9 comprises a partial sectional view of the cylindrical nut of Figures 1 and 2; Figure 10 comprises a plan view of the cylindrical nut; Figure 11 comprises a view simil to Figure 1 of a further embodiment of present invention; Figure 12 comprise fragmentary elevational view, partly i ection, of a modification of the embodimen -Figure 11; and FLt re 13 comprises an elevational view of yet ,a ther embodiment of the present invention.

9s 0 o on 0 0 0 00 t09 0 00 0 09 0 00 0 9g i Z L n.iL 1 rNT APPLICATION 30055 7 Description of the Preferred Embodiments Referring now to Figure 1, a support for supporting a compressive load, such as a roof of a mine, includes a base member 12 having an open end 14 and a hollow interior 16 and a forcing member 18 in the form of a bar having a series of threads 20 thereabout wherein a first end 22 of the bar extends through the first end 14 of the base member 12 into the hollow interior 16.

Referring now to Figures 3 and 4, the base member 12 may comprise a section of ordinary pipe. In one example of the present invention adapted to support a particular roof load, the base member 12 comprises seamless or butt welded carbon oo 5~ steel pipe constructed in accordance with one or more of ASTM standards A53, A106 and A120, Schedule 40. Welded to a second end 24 of the base member oo 12 is a steel bottom plate 26 which is adapted to o'o rest on a floor of a mine.

20 Referring now to Figures 5 and 6, a top plate 28 is welded to a hexagonal lock nut 30 which has a series of female threads 32 surrounding a bore 34. The female threads 32 accept the threads on 0 S 20 of the bar 18 located at a second end 36 there- ,020 5 of. The top plate 28 is adapted to engage a roof of a mine.

It should be noted that the bottom plate 26, the top plate 28 and the lock nut 30 are optional in the sense that the base member 12 and 30 3 bar 18 may be secured to a floor and roof of a mine or other structures, such as a truss, by different means, if desired.

C-IN]' APPLICATION 30055 8 Referring again to Figure 1, means in the form of a mandrel 40 is capable of engaging the threads 20 of the bar 18 at an adjustable position and provides an interfering relationship between the base member 12 and the bar 18 as a compressive load applied thereto. More specifically, and with reference to Figures 7 and 8, the mandrel includes a bore 42 therethrough having female threads 44 disposed thereabout which are sized to accept the threads 20 of the bar 18. The mandrel is preferably circular in cross-section and includes a first end 46 of a first size or diameter, a second end 48 of a second size or diameter and an intermediate portion 50. Preferably, the diameter of the intermediate portion 50 increases linearly uniformly) from the first diameter 46 to the second diameter 48, although the diameter >2 may increase in other than a lineai fashion, if desired. The mandrel 40 thus includes an outer 20 20 surface 52 which is tapered and forms a certain angle with respect to a longitudinal axis 54 of the mandrel If desired, flat surfaces 55 may be proa" vided on the mandrel 40. The flat surfaces afford engagement of the mandrel 40 by a tool (not shown) so that the mandrel 40 may be turned to permit the position of the mandrel 40 on the bar 18 to be adjusted. This, in turn, permits the height of the support 10 to be adjustably variable so that 30 the support 10 can be used to support mine roofs of differing heights.

i ci w PA'iENT APPLICATION 30055 9 Disposed on the first end 22 of the rod 18 is means in the form of a cylindrical nut 60 for centering the bar 18 as relative movement between the bar and pipe occurs in response to the application of compressive load thereto. The cylindrical nut 60 is fabricated of any suitable material, such as metal or plastic, and is shown in greater detail in Figures 9 and 10. The nut 60 includes an interior bore 62 having female threads 64 therein 1 0 adapted to engage the threads 20 on the bar 18.

In the preferred embodiment, the mandrel is fabricated of ductile iron GR 80-55-06 manufactured to ASTM standard A536-80 BHM 187/255. The -od 18 is No. 18 THREADBAR® sold by Dywidag Systems International, Inc., located in Lemont, S" Illinois, a subsidiary of the assignee of the present application, although a different size bar could be used, if desired. Also, in one example of the present invention, the various parts have the 20 dimensions indicated in Table A presented below, although it should be noted that the following dimensions are optional and are not to be construed as limiting the scope of the present invention 0,o 4 (reference letters are indicated in the Figures and 0 r" 25 all dimension are in inches unless otherwise indi- D l cated).

cI, L- c i

PAETAPPLICATION

36.000* 8 0.500 C 4.000 D 3.548 E 6.000 F 0.500 G 2.000 H 6.000 1 3 .250 o J4.535 2.248 005.000 M 5.000 N 3.00 *046 M1.000 3.423 Q 10.5 degrees R 3.423 0000S 0.63 T 0.125 2.000 V 2.248 001 *The lengths of the base member 12 and the bar 18 depend upon the height of the mine roof above the floor and vary with the particular installation.

00 00 0 0 0 0o 0 0 00 0 00 0) 3 0 0 0 0 O 0000

O

0000 0 00 o oo 0 a 9 0 0 0 00 0 0 a o o o a 000400 o 0

II

I i l 00r PATENT APPLICATION 30055 Li Referring again to Figures 1 and 2, before the bar 18 and base member are subjected to compressive loading, the bar 18 is inserted into the base member 12 such that the cylindrical nut 60 and a portion of the mandrel 40 are disposed within the interior 16 of the base member 12. As noted previously, the height of the support 10 is adjusted by turning the mandrel 40 so that the support 10 is disposed between and in contact with the roof and floor of a mine. As a compressive load is applied to the bar 18 and the base member 12, ri'elative movement occurs between the bar 18 and the base member 12 in the axial direction. This axial movement causes radial deformation of the base member 12 due to the interference fit of the mandrel The radial deformation permits the support 10 to yield in response to applied loads in a controlled fashion so that catastrophic failure of the support is prevented. During relative movement of the 20 rod 18 and the base member 12, the cylindrical nut acts to keep the rod 18 centered within the base member 12. As can be seen with reference to Figure 1, the height of the support 10 prior to relative movement of the rod 18 and the base member 12 may 25 be adjusted by rotating the mandrel 40 on the threads 20 to thereby change the elevation thereof. The support 10 may thus be readily adapted for different roof heights as needed.

The material for the base member 12 and relative dimensions of the mandrel 40 and the base member 12 are selected so that the maximum load carrying capacity of the support 10 is less than zir PATENT APPLICATION 30055 12 the calculated buckling capacity thereof by a desired safety margin. Also, the angle Q shown in the drawings may be any angle that provides the desired load handling capacity, although angles within a range between 7 and 15 degrees have been found to result in a most advantageous arrangement.

When a compressive load is first applied, the mandrel 40 trasmits a radially outward force against the walls of the base member 12. The walls of the base member 12 deform as increasing load is applied until the yielding limit of the base member 12 is reached. Thereafter, the support 10 yields and provides a substantially constant and contintn- 15 ous upward force resisting the applied load until the full travel limit of the support 10 is reached.

0a 00 0 0 0 0 O 0000q @O0

I

title: Figure 11 illustrates an alternativ embodiment of the present invention. Ele ts common between Figures 1-10 and 11 are signed like reference numerals. As with th previous 00 0 embodiment, the rod 18 extends in the hollow 0 "o0 0000 interior 16 of the base member 12, In this embodiment, the base member 12 must ave a load carrying ooo 25 capacity in excess of ,the/ reaking load limit of the bar 18. Also, th threaded rod is received within a threaded be of a sliding nut 70. The 00 sliding nut 70 cues a reduced diameter portion 0 00072 which is r ceived within the first end 14 of the base mnemb* 12. and. a second enlarged diameter portion 7 w/hich is disposed atop the end 14 and which has/ diameter at least equal to the inner diameter 6006 III-- I L I*I I II It should be noted that multiple supports according to the present invention can be used together and joined between a common top plate and bottom plate to form a multiple unit for supporting a compressive load.

Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.

o 0o 0 0 Q 8 oo 0 13 EL

Claims

2. The structure of claim i, wherein the mandrel and the base member are circular in cross-section, the base member has an inner diameter of a first size throughout its length and the mandrel has an outer diameter of a second size less than the first size at another end thereof.
3. The structure of claim 2, wherein the outer diameter of the mandrel increases linearly from the second o size to a third size over a portion of its length.
4. The support of claim i, further including means carried by the forcing member and disposed within the base member for centering the forcing member as oo relative movement occurs between the members in response o to application of load thereto.
5. The support of claim 4, wherein the centering means comprises a cylindrical nut disposed on the threads o of the forcing member.
6. The support of claim i, wherein the forcing member comprises a threaded bar.
7. The support of claim i, wherein the base member comprises a pipe which is radially expanded by the S0 forcing member during relative movement of the members.
8. A roof support for a mine, comprising: a pipe having first and second ends and walls defining 14 C 1C C and support capability. A a channel therethrough of circular cross-section having a substantially constant diameter over its length. a bar having first and second ends and threads about an outer periphery thereof; a mandrel having a threaded bore therethrough in engagement with the threads on the bar whereby the mandrel may be positioned at a desired point on the bar by turning the mandrel relative to the bar, tha mandrel further including an outer surface of first diameter smaller than the substantially constant diameter at a first end thereof and of second diameter larger than the substantially constant diameter at a second end thereof opposite the first end; wherein the first end of the bar extends through the first end of the pipe and the mandrel is disposed at least partially within the pipe channel such that the outer surface thereof is in interferring contact with the walls of the pipe; and top and bottom plates disposed on the second ends of the bar and pipe, respectively, and adapted to engage a roof and a floor, respectively, of a mine.
9. The roof support of claim 8, further including a cylindrical nut carried by the bar and disposed within the pipe channel for centering the bar as relative ,o 25 movement occurs between the bar and pipe in response to application of load thereto. The roof support of claim 8, wherein the mandrel includes a longitudinal axis and the mandrel outer ooe~ surface includes an intermediate tapered portion of uniformly increasing diameter and disposed at a certain angle with respect to the longitudinal axis. o 11. The roof support of claim 10, wherein the u o certain angle is within a range between 7 and 15 degrees.
12. The roof support of claim 11, wherein the Oo 35 certain angle is equal to 10.5 degrees.
13. The roof support of claim 8, wherein the substantially constant diameter is equal to 9.01 cm and the second diameter is equal to 11.52 cm. 39 ALI4, 14. The roof support of claim 13, wherein the 15 L- first diameter is equal to 8.69 cm. A structure for supporting a compressive load substantially as hereinbefore described and illustrated.
16. A roof support substantially as hereinbefore described and illustrated. DATED: 16 May 1994 PHILLIPS ORMONDE FITZPATRICK Attorneys for: DYCKERHOFF WIDMANN AKTIENGESELLSCHAFT oa o o aa C 0 SDo 0 o a 6 0 1 C 0 304 0 0 a a a a 16 i i APPLICATION 3005S ABSTRACT OF THE DISCLOSURE YIELDABLE ROOF SUPPORT SYSTEM A support includes a base member having an open end and a hollow interior, a forcing member having an end extending through the open end of the base member into the hollow interior thereof and having threads thereon and a mandrel or sliding nut capable of engaging the threads of the forcing member at an adjustable position and providing an interfering relationship between the base and forc- ing members as a compressive load is applied there- a 15 to. The support is particularly adapted for in 0 supporting the roof of a mine. a o S J I SA