CA2254302A1 - An improved friction washer - Google Patents
An improved friction washer Download PDFInfo
- Publication number
- CA2254302A1 CA2254302A1 CA 2254302 CA2254302A CA2254302A1 CA 2254302 A1 CA2254302 A1 CA 2254302A1 CA 2254302 CA2254302 CA 2254302 CA 2254302 A CA2254302 A CA 2254302A CA 2254302 A1 CA2254302 A1 CA 2254302A1
- Authority
- CA
- Canada
- Prior art keywords
- friction washer
- improved friction
- improved
- rock
- wire mesh
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000011435 rock Substances 0.000 claims abstract description 42
- 238000009434 installation Methods 0.000 claims abstract description 16
- 238000012216 screening Methods 0.000 claims abstract description 14
- 230000007797 corrosion Effects 0.000 claims abstract description 7
- 238000005260 corrosion Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 10
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- 229920006334 epoxy coating Polymers 0.000 claims description 2
- 239000011701 zinc Substances 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 238000013461 design Methods 0.000 description 9
- 238000005065 mining Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 208000027418 Wounds and injury Diseases 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 208000014674 injury Diseases 0.000 description 3
- 238000011900 installation process Methods 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 2
- 229910000639 Spring steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0086—Bearing plates
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Piles And Underground Anchors (AREA)
Abstract
An improved friction washer for securing a wire mesh screening on the protruding ends of rock bolts used for supporting rock in mine openings. The improved friction washer has a central opening which is deformed to fit onto the threaded section of a rock bolt and to then remain in position and thus securing the wire mesh against the rock surface. A
plurality of formed loops are located on one face of the improved friction washer and radially spaced from the center of the central opening at a distance substantially equal to half the outside diameter of a hollow tube so as to allow the loops to fit over an installation tool for securing the friction washer during installation onto the protruding end of the previously installed rock bolt.
An improved friction washer, also known as a gripper plate, with increased resistance to corrosion, an improved and simplified manufacturing process and greatly improved safety for workers when using this device for securing wire mesh onto rock bolts.
plurality of formed loops are located on one face of the improved friction washer and radially spaced from the center of the central opening at a distance substantially equal to half the outside diameter of a hollow tube so as to allow the loops to fit over an installation tool for securing the friction washer during installation onto the protruding end of the previously installed rock bolt.
An improved friction washer, also known as a gripper plate, with increased resistance to corrosion, an improved and simplified manufacturing process and greatly improved safety for workers when using this device for securing wire mesh onto rock bolts.
Description
FIELD OF THE INVENTION
This invention relates to friction washers, and more particularly to an improved push-on friction washer, also known as gripper plates, for securing a wire mesh screening onto the protruding end of rock bolts employed to stabilize rock structures in mining and civil engineering applications.
BACKGROUND OF THE INVENTION
To stabilize openings and improve safety in excavations, threaded end rock bolts have been in general use for some time in supporting rock surfaces and securing wire mesh screening.
Rock bolts are typically installed by insertion into a drilled hole in the rock structure. The rock bolt is retained in these drilled holes by conventional means. In many circumstances a wire mesh screening is secured on the rock surface at the same time as a rock bolt is being installed into drill holes in the same rock surface.
Where wire mesh screening is not secured at the time that rock bolts are installed, it may become necessary to install the wire mesh at time in the future. This can be accomplished by drilling additional holes to anchor the wire mesh through the installation of additional rock bolts. Another obvious method is to secure the wire mesh onto the protruding threaded end of the rock bolt using a second bearing plate and nut. However both of these operations have been 2o found to be inefficient.
The retention of this wire mesh screening using a secondary fastening system has been in use at least since 1982. The method generally employed is that of a bearing plate, commonly referred to as a washer, which secures the wire mesh in position by means of a centrally located opening comprising of a series of teeth, or legs, set into the inside diameter that engage in the threaded section of the protruding rock bolt. Devices which fit the above description have been variously known as friction washers and gripper plates. Examples of these conventional forms of friction washers can be found in Canadian Patent Nos. 1,244.,270 (Gagnon), known as the friction washer, and in Canadian Patent Nos. 2,086,705 (Saab), known as the gripper plate.
As the securement of wire mesh screening has become more widespread in underground mining environments, several characteristics of the above mentioned prior art friction washers have been found to be sufficiently problematic to prevent their universal acceptance and utilization. The present invention is concerned with the provision of an improved friction washer which overcomes the present concerns of the currently available models.
SUMMARY OF THE INVENTION
The present invention relates to a push-on friction washer used for securing wire mesh screening onto the protruding end of a threaded end rock bolt. The friction washer, in accordance with the present invention, comprises of a central opening having a downwardly deformed section which is slotted and formed to engage the threads of the rock bolt, and a plurality of downwardly formed loops spaced from the center of the washer and placed so as to secure the washer on the installation tube during the process of installation onto the rock bolt.
l0 The hollow tube used for holding the friction washer during installation is commonly known as a rock bolt dollie wrench. The tool required for installation is not a part of this embodiment, it should be noted that the tool required is a standard non-modified piece of equipment generally located in mining environments. The friction washer described corrects the many weaknesses of prior art units which will now be described in some detail. The applicant, having first hand 1 S experience in the design and use of this type of device, has overcome the principal problems associated with prior art friction washers in this original design of an improved friction washer.
Previously referred to embodiments Canadian Patent Nos. 1,244,270 (Gagnon), Canadian Patent Nos. 2,086,705 (Saab) are fabricated from approximately 0.06 inch thick tempered mild or spring steel. The improved friction washer is manufactured from readily 20 available and less costly commercial grade mild steel of 0.125 inches thick with no further heat treating or tempering required. The process of eliminating heat treating or tempering eliminates a major cause of variability in the performance of this device, as well a resulting saving in manufacturing is accomplished.
At the present time the device known as the gripper plate requires a specially modified 25 tool to permit installation, the improved friction washer is installed utilizing a standard readily available tool. As a result of replacing the so called tabs with the deformed loop design which said loops are located to secure the washer onto a rock bolt wrench, handling and shipping concerns are also addressed as this unit will easily nest and thus be stackable. Furthermore, said loops may be employed for to suspend hoses and cables and other light hanging applications 30 which may be required in mining situations.
All prior art friction washers exhibit a reduced resistance to corrosion this is a result of the heat treatment or tempering process. This weakness has resulted in this device having limited appeal in mining environments with high sulphide contents. As the improved friction washer is manufactured using untreated mild steel it naturally exhibits an increased resistance to corrosion. Furthermore, the increased thickness of the material compared to other washers for this function, contributes greatly to a longer life expectancy and an increased lateral strength without requiring the need of embossments as on the aforementioned prior arts.
As has often been the case, the aforementioned previously available devices have evolved from the original design embodiments to respond to market demands and as a result of worker experience and due to general concerns and complaints of end users. The designs in current use incorporate design components, invariably pointed or sharp edges, also know as tabs, which have been known to cause injury during the installation process. In a preferred embodiment of the improved friction washer according to the invention, for securing the washer onto the installation tool the aforementioned protruding tabs are replaced by formed loops. This is a significant improvement in response to a safety concern as well as an improvement in the simplification of the manufacturing process. Additional improvement to prevent possible injury to users while taking full advantage of a generally square plan is the inclusion of rounded corners to the improved design.
These and other advantages as listed herein will become more apparent as the invention will now be disclosed, by way of example, with reference to the detailed description of a preferred embodiment illustrated in the accompanying drawings.
DETAILED DESCRIPTION OF A PREFERRED EMBODIIVVIENT
Figure 1 is a top view of the improved friction washer in accordance with the present invention ;
Figure 2 is a side view of the improved friction washer shown in figure 1;
Figure 3 is a detailed view of the central deformed section of the improved friction washer shown in figure 1;
Figure 4 is a detailed view of an individual loop section of the improved friction washer shown in figure 1; and Figure 5 is a schematic view illustrating the process of installation of the wire mesh screening onto the threaded section of an installed rock bolt.
This invention relates to friction washers, and more particularly to an improved push-on friction washer, also known as gripper plates, for securing a wire mesh screening onto the protruding end of rock bolts employed to stabilize rock structures in mining and civil engineering applications.
BACKGROUND OF THE INVENTION
To stabilize openings and improve safety in excavations, threaded end rock bolts have been in general use for some time in supporting rock surfaces and securing wire mesh screening.
Rock bolts are typically installed by insertion into a drilled hole in the rock structure. The rock bolt is retained in these drilled holes by conventional means. In many circumstances a wire mesh screening is secured on the rock surface at the same time as a rock bolt is being installed into drill holes in the same rock surface.
Where wire mesh screening is not secured at the time that rock bolts are installed, it may become necessary to install the wire mesh at time in the future. This can be accomplished by drilling additional holes to anchor the wire mesh through the installation of additional rock bolts. Another obvious method is to secure the wire mesh onto the protruding threaded end of the rock bolt using a second bearing plate and nut. However both of these operations have been 2o found to be inefficient.
The retention of this wire mesh screening using a secondary fastening system has been in use at least since 1982. The method generally employed is that of a bearing plate, commonly referred to as a washer, which secures the wire mesh in position by means of a centrally located opening comprising of a series of teeth, or legs, set into the inside diameter that engage in the threaded section of the protruding rock bolt. Devices which fit the above description have been variously known as friction washers and gripper plates. Examples of these conventional forms of friction washers can be found in Canadian Patent Nos. 1,244.,270 (Gagnon), known as the friction washer, and in Canadian Patent Nos. 2,086,705 (Saab), known as the gripper plate.
As the securement of wire mesh screening has become more widespread in underground mining environments, several characteristics of the above mentioned prior art friction washers have been found to be sufficiently problematic to prevent their universal acceptance and utilization. The present invention is concerned with the provision of an improved friction washer which overcomes the present concerns of the currently available models.
SUMMARY OF THE INVENTION
The present invention relates to a push-on friction washer used for securing wire mesh screening onto the protruding end of a threaded end rock bolt. The friction washer, in accordance with the present invention, comprises of a central opening having a downwardly deformed section which is slotted and formed to engage the threads of the rock bolt, and a plurality of downwardly formed loops spaced from the center of the washer and placed so as to secure the washer on the installation tube during the process of installation onto the rock bolt.
l0 The hollow tube used for holding the friction washer during installation is commonly known as a rock bolt dollie wrench. The tool required for installation is not a part of this embodiment, it should be noted that the tool required is a standard non-modified piece of equipment generally located in mining environments. The friction washer described corrects the many weaknesses of prior art units which will now be described in some detail. The applicant, having first hand 1 S experience in the design and use of this type of device, has overcome the principal problems associated with prior art friction washers in this original design of an improved friction washer.
Previously referred to embodiments Canadian Patent Nos. 1,244,270 (Gagnon), Canadian Patent Nos. 2,086,705 (Saab) are fabricated from approximately 0.06 inch thick tempered mild or spring steel. The improved friction washer is manufactured from readily 20 available and less costly commercial grade mild steel of 0.125 inches thick with no further heat treating or tempering required. The process of eliminating heat treating or tempering eliminates a major cause of variability in the performance of this device, as well a resulting saving in manufacturing is accomplished.
At the present time the device known as the gripper plate requires a specially modified 25 tool to permit installation, the improved friction washer is installed utilizing a standard readily available tool. As a result of replacing the so called tabs with the deformed loop design which said loops are located to secure the washer onto a rock bolt wrench, handling and shipping concerns are also addressed as this unit will easily nest and thus be stackable. Furthermore, said loops may be employed for to suspend hoses and cables and other light hanging applications 30 which may be required in mining situations.
All prior art friction washers exhibit a reduced resistance to corrosion this is a result of the heat treatment or tempering process. This weakness has resulted in this device having limited appeal in mining environments with high sulphide contents. As the improved friction washer is manufactured using untreated mild steel it naturally exhibits an increased resistance to corrosion. Furthermore, the increased thickness of the material compared to other washers for this function, contributes greatly to a longer life expectancy and an increased lateral strength without requiring the need of embossments as on the aforementioned prior arts.
As has often been the case, the aforementioned previously available devices have evolved from the original design embodiments to respond to market demands and as a result of worker experience and due to general concerns and complaints of end users. The designs in current use incorporate design components, invariably pointed or sharp edges, also know as tabs, which have been known to cause injury during the installation process. In a preferred embodiment of the improved friction washer according to the invention, for securing the washer onto the installation tool the aforementioned protruding tabs are replaced by formed loops. This is a significant improvement in response to a safety concern as well as an improvement in the simplification of the manufacturing process. Additional improvement to prevent possible injury to users while taking full advantage of a generally square plan is the inclusion of rounded corners to the improved design.
These and other advantages as listed herein will become more apparent as the invention will now be disclosed, by way of example, with reference to the detailed description of a preferred embodiment illustrated in the accompanying drawings.
DETAILED DESCRIPTION OF A PREFERRED EMBODIIVVIENT
Figure 1 is a top view of the improved friction washer in accordance with the present invention ;
Figure 2 is a side view of the improved friction washer shown in figure 1;
Figure 3 is a detailed view of the central deformed section of the improved friction washer shown in figure 1;
Figure 4 is a detailed view of an individual loop section of the improved friction washer shown in figure 1; and Figure 5 is a schematic view illustrating the process of installation of the wire mesh screening onto the threaded section of an installed rock bolt.
Referring to the drawings, there is shown an improved friction washer 10 manufactured from mild steel which includes a central section 14 with eight formed sections 12 positioned around the perimeter of said opening and adapted to engage the threads of the installed rock bolt. Other prior art friction washers rely on teeth or on so called legs which have been proven to be weakened when subjected to underground blasting and which do not effectively fully contact the circumference of the rock bolt thread as is the situation with the improved design.
The friction washer has a plurality of formed loops 15 which all face in the same direction off plane as the central section and are positioned at an equal distance from the central section and thus foam a secure attachment for the installation tool. As an added benefit of this design, said loops may be used multiply or singly for light hanging applications.
The improved friction washer has a generally square plan of which the four corners are rounded to a radius of one half of an inch, this feature is included to eliminate sharp edges and thus reduce the possibility of injury resulting from inadvertent contact during the installation process. Dimensioning of the improved friction washer is such as to provide adequate support for the wire mesh screening considering that the dimensions of the openings of said mesh that is in common use for this function.
Referring to figure 5, there is shown a threaded end rock bolt 22 installed into a rock structure. A standard rock bolt bearing plate 24 is held securely against the rock surface and tightened by a nut 26. The wire mesh screening 30 is installed onto the protruding thread of the rock bolt using the above disclosed improved friction washer 10. Installation is then completed by setting the improved friction washer onto a standard rock bolt installation tool 20 by fitting the loops 15 around the perimeter of the said installation tool. In practice the operation is simple and can be accomplished using a pneumatic rock drill to push the washer into place, as well this installation process may be done by hand.
Preliminary bench testing, employing industry standard methodology, of the improved friction washer as illustrated, manufactured in mild steel strap of 1/8 inch thickness, resulted in a measured failure load of 2.5 tons. Using this same type of apparatus in actual testing in the past, the applicant consistently recorded lower values for all samples of prior art friction washers. It should be noted that ultimately the wire mesh in common use has a load bearing capacity of much less than this recorded value of 2.5 tons. This increased load capacity would be significant in the future as more mining is carried out in deeper zones and higher stress areas, and where the strand diameter, and therefore the strength of the wire mesh screening may have to be increased.
In reference to the diameter of the installed rock bolt, it should be noted that the two common diameters are the 5/8 inch and the 3/4 inch sizes. Previously available friction washers, Canada 1,244,270 (Gagnon) also, Canada 2,086,705 (Saab), or otherwise known as gripper plates, must be manufactured according to the diameter of the rock bolt onto which the washer will be installed. This results in double stocking for the users, and creates manufacturing problems in scheduling. The improved friction washer as herein disclosed will perform equally well on both size diameters of installed rock bolts resulting in a definite advantage over the prior art examples.
To the list of aforementioned advantages, this improved friction washer is readily treated to greatly improve resistance to corrosion by the common process of galvanization, or zinc coating. As resistance to corrosion has been recognized as a major deterrent in the application and utilization of these devices, this would greatly increase the marketability of friction washers. As an alternative to galvanizing the finished product, epoxy coating would constitute a lower cost protection although this coating would also be somewhat less robust.
Although this invention has been disclosed with reference to a preferred embodiment as shown and described, it is to be understood that it is not limited to such embodiment and that other alternatives are envisaged within the scope of the following claims.
The friction washer has a plurality of formed loops 15 which all face in the same direction off plane as the central section and are positioned at an equal distance from the central section and thus foam a secure attachment for the installation tool. As an added benefit of this design, said loops may be used multiply or singly for light hanging applications.
The improved friction washer has a generally square plan of which the four corners are rounded to a radius of one half of an inch, this feature is included to eliminate sharp edges and thus reduce the possibility of injury resulting from inadvertent contact during the installation process. Dimensioning of the improved friction washer is such as to provide adequate support for the wire mesh screening considering that the dimensions of the openings of said mesh that is in common use for this function.
Referring to figure 5, there is shown a threaded end rock bolt 22 installed into a rock structure. A standard rock bolt bearing plate 24 is held securely against the rock surface and tightened by a nut 26. The wire mesh screening 30 is installed onto the protruding thread of the rock bolt using the above disclosed improved friction washer 10. Installation is then completed by setting the improved friction washer onto a standard rock bolt installation tool 20 by fitting the loops 15 around the perimeter of the said installation tool. In practice the operation is simple and can be accomplished using a pneumatic rock drill to push the washer into place, as well this installation process may be done by hand.
Preliminary bench testing, employing industry standard methodology, of the improved friction washer as illustrated, manufactured in mild steel strap of 1/8 inch thickness, resulted in a measured failure load of 2.5 tons. Using this same type of apparatus in actual testing in the past, the applicant consistently recorded lower values for all samples of prior art friction washers. It should be noted that ultimately the wire mesh in common use has a load bearing capacity of much less than this recorded value of 2.5 tons. This increased load capacity would be significant in the future as more mining is carried out in deeper zones and higher stress areas, and where the strand diameter, and therefore the strength of the wire mesh screening may have to be increased.
In reference to the diameter of the installed rock bolt, it should be noted that the two common diameters are the 5/8 inch and the 3/4 inch sizes. Previously available friction washers, Canada 1,244,270 (Gagnon) also, Canada 2,086,705 (Saab), or otherwise known as gripper plates, must be manufactured according to the diameter of the rock bolt onto which the washer will be installed. This results in double stocking for the users, and creates manufacturing problems in scheduling. The improved friction washer as herein disclosed will perform equally well on both size diameters of installed rock bolts resulting in a definite advantage over the prior art examples.
To the list of aforementioned advantages, this improved friction washer is readily treated to greatly improve resistance to corrosion by the common process of galvanization, or zinc coating. As resistance to corrosion has been recognized as a major deterrent in the application and utilization of these devices, this would greatly increase the marketability of friction washers. As an alternative to galvanizing the finished product, epoxy coating would constitute a lower cost protection although this coating would also be somewhat less robust.
Although this invention has been disclosed with reference to a preferred embodiment as shown and described, it is to be understood that it is not limited to such embodiment and that other alternatives are envisaged within the scope of the following claims.
Claims (7)
1. An improved friction washer used for securing wire mesh screening on a protruding threaded end rock bolt, said friction washer comprising of ;
a) a generally planar base portion being of a generally square shape of four somewhat equal length sides and dimensioned to secure wire mesh screening ;
b) a central opening having eight or more sections on the perimeter of the opening and inclined downwardly and inwardly and adapted to be pushed onto and to conform to the diameter and angularity of the threading of a rock bolt;
c) a plurality of formed loops being radially and circumferentially spaced from the center of above mentioned central opening so to as permit the installation of the washer utilizing a standard rock bolt installation tool;
a) a generally planar base portion being of a generally square shape of four somewhat equal length sides and dimensioned to secure wire mesh screening ;
b) a central opening having eight or more sections on the perimeter of the opening and inclined downwardly and inwardly and adapted to be pushed onto and to conform to the diameter and angularity of the threading of a rock bolt;
c) a plurality of formed loops being radially and circumferentially spaced from the center of above mentioned central opening so to as permit the installation of the washer utilizing a standard rock bolt installation tool;
2. An improved friction washer as defined in claim 1, wherein the four corners of the generally square planar base portion are rounded at a radius of 1/2 inch.
3. An improved friction washer as defined in claim 1 or 2, further comprising of a plurality of formed loops downwardly pointing, spaced equidistantly around the perimeter of the opening.
4. An improved friction washer as defined in claim 1 or 2, further comprising of a central section deformed so as to conform radially to a rock bolt thread.
5. An improved friction washer as defined in claim 1 or 2, wherein the friction washer is made of 1/8 inch, commercial grade, mild steel.
6. An improved friction washer as defined in claim 1 or 2, wherein the friction washer is treated for corrosion resistance using a process of zinc coating.
7. An improved friction washer according to claim 6, wherein the friction washer is treated for corrosion resistance using a process of epoxy coating.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2254302 CA2254302A1 (en) | 1998-11-23 | 1998-11-23 | An improved friction washer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2254302 CA2254302A1 (en) | 1998-11-23 | 1998-11-23 | An improved friction washer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2254302A1 true CA2254302A1 (en) | 2000-05-23 |
Family
ID=29425681
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2254302 Abandoned CA2254302A1 (en) | 1998-11-23 | 1998-11-23 | An improved friction washer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2254302A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2052130A4 (en) * | 2006-08-14 | 2015-03-18 | Hilti Corp | A tensioning device |
| RU174997U1 (en) * | 2017-05-26 | 2017-11-15 | ООО "ОКС-Трейд" | WASHER SUPPORT ANCHOR WITH FIXTOR |
-
1998
- 1998-11-23 CA CA 2254302 patent/CA2254302A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2052130A4 (en) * | 2006-08-14 | 2015-03-18 | Hilti Corp | A tensioning device |
| RU174997U1 (en) * | 2017-05-26 | 2017-11-15 | ООО "ОКС-Трейд" | WASHER SUPPORT ANCHOR WITH FIXTOR |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |