DK180511B1 - Fastener for a tension joint, tension joint and method for forming tension joint - Google Patents
Fastener for a tension joint, tension joint and method for forming tension joint Download PDFInfo
- Publication number
- DK180511B1 DK180511B1 DKPA201970696A DKPA201970696A DK180511B1 DK 180511 B1 DK180511 B1 DK 180511B1 DK PA201970696 A DKPA201970696 A DK PA201970696A DK PA201970696 A DKPA201970696 A DK PA201970696A DK 180511 B1 DK180511 B1 DK 180511B1
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- DK
- Denmark
- Prior art keywords
- compression sleeve
- tension
- clamping rod
- band
- compression
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 230000006835 compression Effects 0.000 claims abstract description 188
- 238000007906 compression Methods 0.000 claims abstract description 188
- 230000003068 static effect Effects 0.000 claims abstract description 12
- 238000004804 winding Methods 0.000 claims description 11
- 238000003825 pressing Methods 0.000 claims description 3
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 238000003780 insertion Methods 0.000 claims 1
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- 230000002093 peripheral effect Effects 0.000 claims 1
- 239000000463 material Substances 0.000 description 28
- 229910000831 Steel Inorganic materials 0.000 description 18
- 239000010959 steel Substances 0.000 description 18
- 239000000853 adhesive Substances 0.000 description 5
- 229920000049 Carbon (fiber) Polymers 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 239000004917 carbon fiber Substances 0.000 description 4
- 239000002390 adhesive tape Substances 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 229910000822 Cold-work tool steel Inorganic materials 0.000 description 2
- 241000765309 Vanadis Species 0.000 description 2
- VGIPUQAQWWHEMC-UHFFFAOYSA-N [V].[Mo].[Cr] Chemical compound [V].[Mo].[Cr] VGIPUQAQWWHEMC-UHFFFAOYSA-N 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000012358 sourcing Methods 0.000 description 2
- 241000283986 Lepus Species 0.000 description 1
- 102000002508 Peptide Elongation Factors Human genes 0.000 description 1
- 108010068204 Peptide Elongation Factors Proteins 0.000 description 1
- 229910000639 Spring steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 229920005594 polymer fiber Polymers 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B21/00—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings
- F16B21/10—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts
- F16B21/20—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts for bolts or shafts without holes, grooves, or notches for locking members
Abstract
A fastener (1) for transferring a tension load to one or more clamped components (8,9) in a tension joint, and a method to establish such a tension joint. The fastener comprises a tension rod (2) and a compression sleeve (3). A band (7) is spirally wound around the compression sleeve (3). The spirally wound band (7) exerts a crushing pressure on the compression sleeve (3). The band (7) is wound spirally on the compression sleeve (3). The compression sleeve (3) is compressed by the spirally wound band (7). The compression sleeve (3) applies contact pressure on the tension rod (2). The contact pressure of the compression sleeve (7) on the tension rod (2) creates static friction that locks the compression sleeve (3) to the tension rod (2).
Description
TITLE Fastener for a tension joint, tension joint and method for forming tension joint.
TECHNICAL FIELD The disclosure relates to a fastener for a tension joint for transferring an applied tension load through the joint by way of one or more clamped components, and to a method for forming such a tension joint.
BACKGROUND A fastener is a hardware device that mechanically joins or affixes two or more parts or objects together. A bolt is a rod or pin (typically metal, especially steel) for fastening objects together that usually has a head at one end and a screw thread at the other and is secured by a nut. Bolts are used to create a bolted joint. This is a combination of the nut applying an axial clamping force and the shank of the bolt acting as a dowel, pinning the joint against sideways shear forces. For this reason, many bolts have a plain unthreaded shank as this makes for a better, stronger dowel. Bolted Joints and stud joints are common elements in construction and machine design. They consist of fasteners that capture and join other parts or objects, and are secured with the mating of screw threads. There are two main types of bolted joint designs: tension joints and shear joints.
DK 180511 B1 2 In the tension joint, the bolt and clamped components of the joint are designed to transfer an applied tension load through the joint by way of the clamped components by the design of a proper balance of joint and bolt stiffness.
The joint should be designed such that the clamp load is never overcome by the external tension forces acting to separate the joint.
If the external tension forces overcome the clamp load (bolt preload) the clamped components will separate, allowing relative motion of the components.
A challenge with bolted joints is the fact that it is very difficult to tension bolts exactly to the required level.
This is caused by variations in friction and tolerances, especially when the bolts are tensioned by rotating the nut by applying torque to the nut.
When using a hydraulic tensioning apparatus and rotating the nut essentially unloaded, the tensioning accuracy is improved but it is still far from perfect.
When using hydraulic tensioning it is also avoided that the shank is loaded by torque, which leads to a higher overall load on the shank.
In bolted connections that need to be able to withstand very high tension loads, such as e.g. bolted connections that clamp together the flanges of tower sections of large wind turbines, it can be a significant challenge to fit tension bolts of sufficient strength in a sufficiently large number, i.e. in a sufficiently close pattern to arrive at a bolted connection with sufficient strength.
One challenge is that increasing the bolt diameter increases the spacing between the bolts (e.g. since there needs to be space between the nuts of
DK 180511 B1 3 neighbouring bolts). For the largest wind turbines these bolted connections between the wind turbine tower sections hit the engineering limits of what is possible with a conventional bolted connection.
Other solutions have been provided in the art. One solution is to use a so-called shrink disc around an area of a shaft and apply the necessary pressure to transfer the load in a friction connection. Shrink disks are though complex, voluminous and relatively expensive. DE102016209395 discloses a similar, solution in the form of a fastening element for tolerance compensation in the joining of components with a fastening bolt for fastening to a first component, wherein the fastening bolt has a mounting portion and a cylindrical shaft extending from the fixing portion, and wherein a clamping sleeve is provided which is cylindrical on the shaft is slidably disposed.
SUMMARY It is an object to provide a tension joint for transferring an applied tension load through the joint by way of one or more clamped components, that overcomes or at least reduces the problems mentioned above. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.
DK 180511 B1 4 According to a first aspect, there is provided a fastener for applying tension load to clamp one or more members, the fastener comprising: - a tension rod,
- a first compression sleeve with an axially directed contact surface for applying a clamping pressure on one of the one or more members, and - a first band spirally wound around the first compression sleeve,
- the tension rod extending through the first compression sleeve, - the spirally wound first band applying a compression pressure to the first compression sleeve, - the first compression sleeve being compressed by the compression pressure applied by the first spirally wound band, - the first compression sleeve applying pressure to the tension rod by the first compression sleeve being compressed, and - the first compression sleeve being locked to the tension rod by static friction between the tension rod and the first compression sleeve caused by the pressure that the first compression sleeve exerts on the tension rod.
The maximum tensile load that can be handled by a bolt of a given diameter and material is significantly lower than the maximum tensile load that can be applied to a rod of the same diameter and material.
This is caused by the reduction in diameter caused by the male thread and due to the notch effect (fatigue) of the root of the male thread, and (if present) by the transition between the head and shank.
Removing the thread and bolt head increases tensile strength by over 30 %.
DK 180511 B1
Further, there is a wider freedom of selection of materials and material treatments for a simple rod than for a threaded bolt (since a rod does not need to be provided with tread and 5 head). A simple rod that does not require machining allows for optimal material selection for maximum tensile strength.
Thus, a ductile material with a high Young's modulus, and a high yield- and ultimate tensile strength can be chosen.
This freedom in e.g. steel material selection increases the tensile strength from 1000 N/mm2 for a bolt to >1500 N/mm2 for a tension rod.
Combined, these effects cause a significant difference in the maximum tensile load that can be handled by a bolt and a rod of the same diameter.
A rod can under certain circumstances handle double the tensile load of a bolt of the same diameter.
Thus, removing the tread and the head of a bolt, i.e. using a simple rod, allows a reduction in diameter of the tensile rod compared to a bolt of the same tensile strength.
Further, the combination of the sleeve and the band wound around the sleeve has an outer diameter that is significantly smaller than the largest diameter of the nut.
Thus, the tensile rods can be significantly more closely spaced than equally strong bolts, allowing for more fasteners to be used in a given area, i.e. resulting in a closer and more homogenous pattern of fasteners and a stronger joint.
Compared to a shrink disc solution of the prior art, an improvement or advantage may lie therein that the tension
DK 180511 B1 6 joint according to the first aspect is able to obtain same or similar pressures, as obtainable by use of a shrink disc, by the windings of the band around the complete circumference of the compression sleeve. Further advantages in relation to the shrink disc or similar solution lie in the reduced weight, in that there is no or only limited need for tightening bolts as compared to the relative high number of tension bolts used in a typical shrink disc. Moreover, sourcing of a band is easier at remote locations than sourcing of the more elaborate solution of the shrink disc. According to a possible implementation of the first aspect the first compression sleeve is provided with a cylindrical bore with a diameter before compression of the first compression sleeve that allows the tension rod to be inserted in the cylindrical bore with a clearance. According to a possible implementation of the first aspect the tension rod is pre-tensioned using a tensioning appratus or apparatus before the first compression sleeve is locked to the tension rod. According to a possible implementation of the first aspect the tension apparatus is a hydraulic tension apparatus.
According to a possible implementation of the first aspect the first band is wound under tension at least once around the outer circumference of the first compression sleeve. According to a possible implementation of the first aspect the pressure provided by winding the first band around the
DK 180511 B1 7 outer circumferential surface of the first compression sleeve provides a friction-fit interconnection between the first compression sleeve and the tension rod.
According to a possible implementation of the first aspect the fastener comprises a second compression sleeve , the second compression sleeve being arranged over the tension rod with the axially directed contact surface of the second compression sleeve directed to the first compression sleeve, the axially directed contact surface of the fist compression sleeve being directed to the second compression sleeve, the second compression sleeve being locked to the tension rod by a second band wound spirally around the second compression sleeve.
According to a possible implementation of the first aspect the second compression sleeve is locked to the tension rod before the first compression sleeve is arranged on the tension rod.
According to a possible implementation of the first aspect the first and/or second compression sleeve are circumferentially divided into multiple parts that together surround the tension rod.
According to a possible implementation of the first aspect a plurality of spirally wound bands is provided around the first and/or second compression sleeve, the spirally wound bands of a plurality of spirally wound bands preferably being axially distributed over the axial extent of the compression sleeve concerned.
DK 180511 B1 8 According to a possible implementation of the first aspect the tension rod is at one end anchored to or integrally connected with a member.
According to a possible implementation of the first aspect the band is made of steel or carbon fiber.
According to a possible implementation of the first aspect the band is made of a sheet of steel or spring band steel. According to a possible implementation of the first aspect the band of steel or spring band steel has a thickness of
0.05 to 2.5 mm.
According to a possible implementation of the first aspect the tensile stress when winding the band is 50 to 450 N/mm2. wherein the winding comprises 2 to 400 layers.
According to a possible implementation of the first aspect the tension rod is made from a composite comprising carbon fiber, and the band is preferably also made of a carbon fiber material, which is especially useful in the aerospace industry, where weight is an important factor.
According to a possible implementation of the first aspect, - the spirally wound second band applies a compression pressure to the second compression sleeve, - the second compression sleeve is compressed by the compression pressure applied by the second spirally wound band,
DK 180511 B1 9 - the second compression sleeve applies pressure to the tension rod by the second compression sleeve being compressed, and - the second compression sleeve is locked to the tension rod by static friction between the tension rod and the second compression sleeve caused by the pressure that the second compression sleeve exerts on the tension rod.
According to a possible implementation of the first aspect the axially directed contact surface applies a clamping pressure on one of the one or more members.
According to a possible implementation of the first aspect the compression sleeve has a reduced diameter section extending from the longitudinal end of the compression sleeve opposite to the axially directed contact surface towards the longitudinal end with the axially directed contact surface.
According to a possible implementation of the first aspect the compression sleeve has an enlarged diameter section at the longitudinal end that is provided with the axially directed contact surface.
According to a possible implementation of the first aspect a tapered portion connects the reduced diameter section to the enlarged diameter section.
According to a possible implementation of the first aspect the material for the tension rod is a molybdenum-vanadium- alloyed steel, such as e.g. Uddeholm Orvar® Supreme, commercially available from Uddeholms AB, Sweden. Uddeholm
DK 180511 B1 10 Orvar® Supreme is a molybdenum-vanadium-alloyed steel which has a high level of resistance thermal shock and thermal fatigue, good high-temperature strength, excellent toughness and ductility in all directions, good machinability and polishability, Excellent through-hardening properties, and good dimensional stability during hardening. This material is not suitable for manufacturing threaded bolts. According to a possible implementation of the first aspect the material for the tension rod is a chromium-molybdenum- vanadium alloyed steel, such as e.g. Uddeholm Vanadis® 4 Extra SuperClean, commercially available from Uddeholms AB, Sweden. Uddeholm Vanadis® 4 Extra SuperClean 1s a chromium- molybdenum-vanadium alloyed steel which is hase very good ductility, high abrasive-adhesive wear resistance, high compressive strength, good dimensional stability during heat treatment and in service, very good through-hardening properties good temper back resistance good machinability and grindability.
According to a possible implementation of the first aspect the material for the tension rod is, a Cr-Mo-V-N alloyed cold work tool steel, such as e.g. Vancron SuperCleand8, commercially available from Uddeholms AB, Sweden. Uddeholm Vancron SuperClean is a Cr-Mo-V-N alloyed cold work tool steel, which has very high adhesive wear resistance, very high galling resistance, good chipping and cracking resistance, high compressive strength, good through hardening properties, good dimensional stability in hardening, very good resistance to tempering back and good WEDM properties
DK 180511 B1 11 According to a possible implementation of the first aspect the material for the tension rod is an oil-air-vacuum- hardening steel, such as e.g. Uddeholm Viking®, commercially available from Uddeholms AB, Sweden. Uddeholm Viking is an oil-air-vacuum-hardening steel which is has good dimensional stability during heat treatment, good machinability and grindability, excellent combination of toughness and wear resistance.
According to a second aspect, there is provided a tension joint for transferring an applied tension load through the joint by way of one or more clamped members, the tension joint comprising a fastener according to the first aspect or according to any possible implementations of the first aspect.
According to a possible implementation of the second aspect the or more clamped members are each provided with a bore, with the tension rod extending through the bores in the one or more clamped members.
According to a third aspect, there is provided a method for creating a tension joint for transferring an applied tension load through the joint by way of one or more clamped members, the method comprising: - inserting a tension rod through a member, - arranging a first compression sleeve with an axially directed contact surface over the tension rod with the axlally directed contact surface in contact with a surface of the member, - tensioning the tension rod,
DK 180511 B1 12 - spirally winding a first band under tension at least once around the outer circumference of the first compression sleeve, thereby: o applying a compression pressure to the first compression sleeve, o compressing the first compression sleeve, o the first compression sleeve applying pressure to the tension rod by the first compression sleeve being compressed, and o locking the compression sleeve to the tension rod by static friction between the tension rod and the first compression sleeve caused by the pressure that the first compression sleeve exerts on the tension rod.
According to a possible implementation of the third aspect the method comprises fixing the band to the outer circumference of the compression sleeve by applying glue, adhesive, by applying double sided adhesive tape, or by welding.
These and other aspects will be apparent from the drawings and the embodiment (s) described below.
BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings (drawings not to scale), in which:
DK 180511 B1 13 Fig. 1 is a sectional view of a tension joint and a fastener according to an embodiment; Fig. 2 is a side view of the tension joint and fastener of Fig. 1; Fig. 3 is a top view of the tension joint and fastener of Fig. 1; Fig. 4 is a detail of Fig. 3 illustrating details of a spirally wound band; Fig. 5. is a top view of a compression sleeve used in the fastener of Fig. 1; Fig. 6. is a bottom view of a compression sleeve used in the fastener of Fig. 1; Fig. 7. is a top view of another embodiment of the compression sleeve used in the fastener of Fig. 1; Fig. 8. is a bottom view of the compression sleeve of Fig. 7; Fig. 9 is an exploded view of the tension joint of Fig. 1; Fig. 10 is a sectional view of the tension joint and a fastener according to another embodiment, Fig. 11 is a sectional view of the tension joint and a fastener according to yet another embodiment, Figs. 12 and 13 illustrate the tension joint according to an embodiment together with a tensioning tool, Figs. 14 and 15, illustrated another embodiment of a tension joined together with the tensioning tool, and Fig. 16 illustrates a conventional bolted joint and same strength tension joint according to an embodiment.
DK 180511 B1 14 Figs. 1 to 6 and 9 show a first embodiment of the tension joint and tension fastener. The tension joint clamps two members 8 and 9 together with a tension force. The fastener 1 transfers a tension load to the clamped components 8,9 in the tension joint. The members 8 and 9 are each provided with an identical diameter bore through the member 8,9 concerned. The bores are aligned and a tension rod 2 of the fastener 1 is inserted through the aligned bores of both members 8,9. The tension rod 2 protrudes with both its ends from the clamped members 8,9. A first compression sleeve 3 is arranged over the end of tension rod 2 that protrudes from the first member 8. The first compression sleeve has an axially directed contact surface 4 that is in contact with a surface of the first member 8 and applies a clamping pressure on the first member
8. A first band 7 is spirally wound (coiled) under tension around the first compression sleeve 3. The spirally wound first band 7 exerts a crushing/compression pressure on the first compression sleeve 3. The first compression sleeve 3 is compressed by the spirally wound first band 7. By means of its compression the first compression sleeve 7 applies contact pressure on the tension rod 2. The contact pressure of the first compression sleeve 7 on the tension rod 2 creates static friction that locks the first compression sleeve 7 to the tension rod 2. A second compression sleeve 3’ is arranged over the end of tension rod 2 that protrudes from the second member 9. The second compression sleeve has an axially directed contact
DK 180511 B1 15 surface that is in contact with a surface of the second member 9 and applies a clamping pressure on the second member 9. A second band 7’ is spirally wound (coiled) under tension around the second compression sleeve 3’. The spirally wound second band 7’ exerts a crushing/compression pressure on the second compression sleeve 3’. The second compression sleeve 3’ is compressed by the spirally wound second band 7’. By means of its compression the second compression sleeve 7’ applies contact pressure on the tension rod 2. The contact pressure of the second compression sleeve 7’ on the tension rod 2 creates static friction that locks the second compression sleeve 7’ to the tension rod 2. In an embodiment the second compression sleeve 3’ is locked to the tension rod 2 before the tension rod is inserted into the bores through the members 8,9, and before the first compression sleeve 3 is arranged on the tension rod 2. The tension rod 2 with the second compression sleeve 37 already locked thereto, is inserted through the members 8,9 with the axial contact surface of the second compression sleeve 3’ facing a surface of the second member 9. Next, the first compression sleeve 3 is arranged over the tension rod 2 with the axial contact surface 4 of the second compression sleeve 3 facing a surface of the first member 8. Then, a tensioning apparatus, such as e.g. a hydraulic tensioning apparatus is used to tension the tension rod 2 (possibly using a tensioning tool 10 as shown in Figs 12 to 15). Thus, the tension rod 2 is pre-tensioned by the tensioning apparatus before the first compression sleeve 3 is locked to the tension rod 2.
DK 180511 B1 16 Thereafter, the first band 7 is wound under tension around the first compression sleeve 3 whilst the tension apparatus maintains the desired tension in the tension rod 2 (pre- tensioning the tension rod 2). Once the first band 7 has been wound around the first compression sleeve 3 and locks the first compression sleeve 3 to the tension rod 2, the tensioning apparatus is removed.
The first and second compression sleeves 3,3’ are annular members that are provided with a cylindrical bore with a diameter before compression of the first or second compression sleeve 3,3’ that allows the tension rod 2 to be inserted in the cylindrical bore with a clearance.
The first and second compression sleeves 3,3’ have a reduced diameter section extending from the longitudinal end of the first or second compression sleeve 3,3’ opposite to the axially directed contact surface 4 towards the longitudinal end with the axially directed contact surface 4. The first and second compression sleeve 3,3’ have an enlarged diameter section at the longitudinal end that is provided with the axially directed contact surface 4, thus allowing the axially directed contact surface 4 to have a relatively large surface area to distribute and reduce the contact pressure with the first member 8. A tapered portion connects the reduced diameter section to the enlarged diameter section.
The start of the first band 7 is secured to reduced diameter section of the first compression sleeve 3 by glue, adhesive, double sided adhesive tape or welding. Thereafter, the first
DK 180511 B1 17 band 7 is spirally coiled or wound onto the first compression sleeve 3 (at least one complete winding) while applying controlled tension. After the required number of windings of first band 7 has been applied, the first compression sleeve 3 is locked to the tension rod 2 by the first compression sleeve being compressed under the load of the coiled first band 7, in particular, the reduced diameter section of the first compression sleeve 3 being compressed by the spirally wound band 7, and the contact pressure of the inner surface of the bore through the compression sleeve 3 on the outer surface of the tension rod 2 causing static friction that locks the compression sleeve 3 to the tension rod 2, i.e. by providing a friction-fit interconnection between the first compression sleeve 7 and the tension rod 2. The free end of the first band 7 is secured to the coil by applying glue, adhesive, double sided adhesive tape or welding to ensure that the first band 7 does not unwind or release tension. Since there is no tension on the free end of the band, a relatively weak connection is required to secure the first band 7 from unwinding. The same procedure is used to lock the second compression sleeve 3’ to the tension rod 2, using the second band 7’ but as mentioned above, this procedure is preferably performed before the tension rod 2 is inserted through the bores in the first and second members 8,9. The second compression sleeve 3’ is arranged over the tension rod 2 with the axially directed contact surface of the second compression sleeve 3’ directed to the first compression sleeve
3. The axially directed contact surface 3 of the fist
DK 180511 B1 18 compression sleeve 3 1s directed to the second compression sleeve 3’. The second compression sleeve 3’is locked to the tension rod 2 by the second band 7’ wound spirally around the second compression sleeve 37.
Figs. 7 and 8 show another embodiment of the tension fastener
1. In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity. In the embodiment of Figs. 7 and 8 the first and/or second compression sleeve 3,3’ are circumferentially divided in two halves, i.e. the first and/or second compression sleeve 3,3’ are circumferentially divided into multiple parts that together surround the tension rod 2. This renders it under circumstances easier to arrange the compression sleeve 3 around the tension rod 2. Fig. 10 shows another embodiment of the tension fastener 1. In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity. In the embodiment of Fig. 10 the tension rod is at one end anchored to or integrally connected with a second member 9’. Thus, there is no need for a second compression sleeve 3’. The tension rod 2 is in the shown embodiment integral, i.e. one piece of material with the second member 9’, but it is understood that the tension rod 2 could also be anchored into the second member 9’, e.g. when the second member is a foundation or wall, such as e.g. a concrete foundation or
DK 180511 B1 19 concrete wall.
The tension rod 2 is inserted through the first member 8, the first compression sleeve 3 is arranged over the tension rod 2 and the axially directed contact surface 4 is brought into contact with the surface of the first member 8. Thereafter, a tensioning tool tensions the tension rod 2. Whilst the tensioning apparatus tensions the tension rod 2, the first band 7 is wound under tension around the reduced diameter section of the compression sleeve 3, thereby locking the first compression sleeve 3 to the tension rod 2. Thereafter, the tensioning device X is deactivated and removed.
Fig. 11 shows another embodiment of the tension fastener 1. In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity.
In the embodiment of Fig. 11 a plurality of spirally wound bands 7,7" is provided around the first and/or second compression sleeve 3,3’. In Fig. 11 four bands are spirally wound around each sleeve 3,3’. However, it is understood that the number of side-by-side spirally wound bands 7,77 is selected in accordance with the circumstances and the plurality of spirally wound bands on a single sleeve 3,3’ can be any number above one.
The number of side-by-side spirally wound bands 7,7" is selected in accordance with the need to reduce the width of the individual spirally wound bands 7,7’. The spirally wound bands 7,7’ of a plurality of spirally wound bands 7,7’ are axially distributed over the axial extent of the (reduced diameter section of the) compression sleeve 3,3’ concerned.
Having a band of a lesser width renders it more
DK 180511 B1 20 flexible and capable of going through bends, which can be needed if the fastener 1 is located close to a wall, thereby restricting movement around the first or second compression sleeve 3,3’.
In an embodiment there are more than two members 8,9 clamped together by the tension fastener 1. The first and second bands 7,7” are preferably formed of steel of high tensile strength and low elongation factor. Other high tensile strength metals such as e.g. titanium are also suitable as band material. Other suitable materials for the band material are fiber based bands comprising high strength fibers, e.g. polymer fibers, glass fibers or carbon fibers.
In embodiments, the material thickness of the first and second band 7,7’ may be in the range of 0.1 to 5 mm. It may be advantageous to use as thin a band as possible which is still able to withstand the tension imposed on the band in order to provide pressure to the interconnecting parts. The thickness may be such as 0.25 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, Or other appropriate material thicknesses. In embodiments, the width of the band may be in the range of 1 to 100 mm. The specific width may be selected in accordance with the dimensions of the tension rod 2 and the compression sleeve 3. The first and second band 7 should be ductile and have a high yield- and ultimate tensile strength. A suitable material for
DK 180511 B1 21 most cases would be spring steel.
A surface treatment would generally not be beneficial.
The first and second compression sleeves 3,3’ should be ductile.
The material should not be too stiff, as it has to deform to make a secure grip on the tension rod.
Most metals can be used for his.
It would be advantageous to use the same material as for the tension rod 2, as the heat expansion coefficient would be exactly the same.
The material should also have a high coefficient of friction together with the tension rod material.
A surface treatment is not needed, however a surface treatment increasing the coefficient of friction would be advantageous.
The term “band” as used herein covers any elongated strip of thin material, such as e.g. a ribbon, band or strip.
The first and/or second band 7,7’ are wound spirally around the respective compression sleeve 3,3’ under considerable tension and suitably secured against unwinding and against lowering of the tension.
The spirally wound first and/or second band(s) 7,7’ exert a crushing pressure on the compression sleeve 3, which is thereby compressed and applies a crushing pressure on the tensile rod 2. The crushing pressure of the first and/or second compression sleeve 3,3’ on the tensile rod 2 creates friction that locks the first and/or second compression sleeve 3,3" to the tensile rod 2. The axial force required to move the first and/or second compression sleeve 3, 3’ relative to the tensile rod 2 is the product of the contact area between
DK 180511 B1 22 the inner surface of the first and/or second compression sleeve 3,3’ and the outer surface of the tensile rod 2 times the crushing (contact) pressure times the coefficient of static friction between the inner surface of the compression first and/or second sleeve 3,3’ and the outer surface of the tensile rod 2. Example 1 Steel tension rod with 10 mm diameter (Alloy steel, Q & T) Steel compression sleeve 20 mm length (Alloy steel, Q & T) Contact area: nm x diameter x sleeve length: 628.32 mm2 Compression pressure with 59 windings, with a 0.03 mm band thickness is conservatively set: 375 N/mm2 Coefficient of static friction (steel-steel clean and dry) 0,5 - 0,8 (lowest value used) Force required to overcome static friction between sleeve and rod: 628.32 mm2 x 375 N/mm2 x 0,5 = 117,810 N Minimum ultimate tensile load for a 10 mm diameter rod of same material as the property class 12.9 bolt based on a 78.5 mm2 nominal stress area: 94,200 N Minimum ultimate tensile load for a 10 mm diameter rod with steel selected optimum for tensile load strength and not requiring any machining has a tensile strength of 1500 N/mm2 and based on a 78,5 mm2 nominal stress area the result is
117.750 N For comparison: an M12 thread bolt, property class 12.9, nominal stress area 88 mm2 has a minimum ultimate tensile
DK 180511 B1 23 load: 105,750N (according to Peder Klit and Niels L. Pedersen. Machine Elements Analysis and Design. Polyteknisk forlag, 2nd edition, 2014. ISBN 978-87-502-1068-9.). Width across corners of an M12 nut/head are 20,78 mm.
The outer diameter of the band wound spirally around the compression sleeve of the example 1 can be as low as 15.5 mm.
Thus, the tension join according to the present disclosure takes up significantly less space than a bolt of a comparable strength. Thus, the overall strength of a connection comprising a plurality of tension joints according to the present disclosure compared to the overall strength of a connection with plurality conventional bolts is significantly higher, since the tension joints according to the present disclosure are stronger and can be placed in a more dense pattern, i.e. there can be more of them in the same area.
Figs. 12 and 13 illustrate an embodiment of tension joint similar to the tension joint illustrated above, together with a tensioning tool 10. The tensioning tool 10 is designed to be clamp with high pressure onto the free end of the tension rod 2. The free end of the tension rod 2 is received in an axial bore in the tensioning tool 10. Hereto, the tension 2 is provided with oppositely directed conical surfaces and a circumferential groove therebetween. Further, the tensioning tool 10 is provided with a plurality of circumferentially distributed axially extending slits that facilitate compression of the tensioning tool 10 onto the free end of the tension rod 2. The tensioning tool 10 is suitable for
DK 180511 B1 24 being grasped by a hydraulic tensioning device (not shown) to thereby apply pretension to the tension rod 2 before the band 7, 77 is wound around the compression sleeve 3. After winding the band 7, 7’ around the compression sleeve 3, the tensioning tool 10 is removed.
The free end of the tension rod 2 may be severed after removal of the tensioning tool 10. Figs. 14 and 15 illustrate another embodiment of a tension joint similar to the tension joint illustrated above, together with a tensioning tool 10. The tensioning tool 10 is similar to the tensioning tool 10 of Figs. 12 and 13, except for the surface of the axial bore of the tensioning tool 10. In the present embodiment the inner surface of the bore is ribbed, e.g. in an undulating pattern, with the ribs extending circumferentially.
The material of the tensioning tool 10 is in this embodiment substantially harder than the material of the tension rod 2, so that the circumstantially extending ribs deform the tension rod 2 upon compression of the tensioning tool 10, thereby providing for increased capacity to of the tensioning tool 10 to grip the tension rod 2. As shown this embodiment this may allow for an axial shorter overlap between the free end of the tension rod 2 and the tensioning tool 10. In Figs. 14 and 15 the band 7 has been wound around the upper compression sleeve 3 and the tensioning tool 10 can be removed (e.g. by severing the free end of the tension rod 2). Fig. 16 illustrates a conventional bolted joint comprising 3 bolts and nuts 11 together having same strength as the five tension joints 1 according to an embodiment.
The five tension joints 1 according to the embodiment way is substantially
DK 180511 B1 25 less than the 3 bolts and nuts 11 and consume less space and can be arranged closer to the flange 12. The various aspects and implementations have been described in conjunction with various embodiments herein.
However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims.
In the claims, the word "comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.
The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.
The reference signs used in the claims shall not be construed as limiting the scope.
Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure.
Claims (13)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA201970696A DK180511B1 (en) | 2019-11-14 | 2019-11-14 | Fastener for a tension joint, tension joint and method for forming tension joint |
| PCT/DK2020/050310 WO2021093925A1 (en) | 2019-11-14 | 2020-11-13 | Fastener for a tension joint, tension joint, and method for forming tension joint |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA201970696A DK180511B1 (en) | 2019-11-14 | 2019-11-14 | Fastener for a tension joint, tension joint and method for forming tension joint |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| DK180511B1 true DK180511B1 (en) | 2021-06-03 |
| DK201970696A1 DK201970696A1 (en) | 2021-06-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DKPA201970696A DK180511B1 (en) | 2019-11-14 | 2019-11-14 | Fastener for a tension joint, tension joint and method for forming tension joint |
Country Status (2)
| Country | Link |
|---|---|
| DK (1) | DK180511B1 (en) |
| WO (1) | WO2021093925A1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2734544A (en) * | 1956-02-14 | Camming locking features | ||
| US1927705A (en) * | 1928-02-14 | 1933-09-19 | Internat Safety Lock Nut Corp | Lock nut |
| DE3742585C1 (en) * | 1987-12-16 | 1989-03-30 | Audi Ag | Screw connection |
| DE102007018025A1 (en) * | 2007-04-17 | 2008-10-23 | Nordex Energy Gmbh | Wind turbine tower |
| CN101886653B (en) * | 2010-07-12 | 2012-07-25 | 朱建华 | Fastening device |
| DE102016209395A1 (en) * | 2016-05-31 | 2017-11-30 | Arnold Umformtechnik Gmbh & Co. Kg | Fastening element for tolerance compensation |
-
2019
- 2019-11-14 DK DKPA201970696A patent/DK180511B1/en active IP Right Grant
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2020
- 2020-11-13 WO PCT/DK2020/050310 patent/WO2021093925A1/en active Application Filing
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| Publication number | Publication date |
|---|---|
| DK201970696A1 (en) | 2021-06-03 |
| WO2021093925A1 (en) | 2021-05-20 |
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Effective date: 20210603 |