Composite washer for force indication and prevention of loosening of fasteners

Abstract

The present invention relates to a composite washer for force indication and prevention of loosening of a fastener. The composite washer includes an upper part having a circumferential extension around an axis, an elastic part having a circumferential extension around the axis, and a base part having a circumferential extension around the axis. The upper part, the elastic part, and the base part are connected to each other, the elastic part is disposed between the upper part and the base part, and there is a central opening having an extension along the axis over the entire upper part, the elastic part, and the base part. Further, the composite washer is arranged in a primary state where the elastic part is visible on its side surface, and the composite washer is arranged in a secondary state where the elastic part is compressed by the upper part and the base part such that the elastic part is hidden by at least one of the upper part and the base part on its side surface. In this way, a composite washer is provided that indicates the tightening force applied to the fastener and cancels the loosening of the fastener.

Description

Technical Field

[0001] The present invention relates to the field of washers, and more particularly to washers for improving the fastening of fasteners such as bolts, nuts, screws, or clamps.

Background Art

[0002] Fasteners such as bolts, screws, nuts, or clamps are widely used to mechanically join or fix two or more objects together. Depending on the situation, the fastener needs to be applied with a specific tightening force. If the tightening force is less than required, the fastener may loosen, which can lead to serious consequences. On the other hand, if the tightening force is greater than necessary, excessive force is applied to tighten the fastener, which may damage either the object being joined by the fastener or the fastener itself. Today, torque wrenches and screwdrivers equipped with preset torque meters are designed to solve this problem by enabling the user to control the tightening force applied. However, when using such tools, a cumbersome process is required to tighten multiple fasteners that require different tightening forces. Furthermore, many handheld tools are heavy and expensive, and may not even be practical for fasteners that require a large tightening force. Additionally, using a handheld power tool to tighten a fastener located in an inaccessible or exposed location can be dangerous or even impossible due to lack of space.

[0003] Also, a fastener applied with exactly the required tightening force may loosen unexpectedly due to repetitive forces or vibrations that may slowly loosen the fastener. To prevent loss of the tightening force for fastening the fastener, metal washers are commonly used. Therefore, in the prior art, it is necessary to ensure that the fastener is applied with the correct tightening force while also ensuring that the fastener remains securely tightened.

Summary of the Invention

[0004] At least some of the above-mentioned drawbacks are overcome by the present disclosure according to the independent claims. Preferred embodiments are described in the dependent claims.

[0005] According to one aspect of the present disclosure, a composite washer for force display and prevention of loosening of a fastener is provided. The composite washer includes an upper portion having a circumferential extension around an axis, an elastic portion having a circumferential extension around the axis, and a base portion having a circumferential extension around the axis. Here, the upper portion, the elastic portion, and the base portion are connected to each other. Here, the elastic portion is disposed between the upper portion and the base portion. Here, there is a central opening having an extension along the axis over the entire upper portion, the elastic portion, and the base portion. Here, the composite washer is disposed in a primary state where the elastic portion is visible from its side. Here, the composite washer is disposed in a secondary state where the elastic portion is compressed by the upper portion and the base portion and the elastic portion is hidden by at least one of the upper portion and the base portion from its side.

[0006] The present disclosure is based on the insight that the provided composite washer provides the user with a visual aid indicating whether a sufficient amount of tightening force has been applied to fasten the fastener. This indication is shown when the elastic portion is no longer visible on the side of the composite washer, which is due to a sufficient amount of tightening force being applied. By changing the rigidity of the elastic portion, for example by changing the shape of the elastic portion, the compression force required to compress the composite washer into its secondary state can be changed as desired. This enables the supply of a plurality of composite washers, each having an individual rigidity level, for a plurality of fasteners, each having an individual required tightening force. This allows the user to quickly fasten a plurality of fasteners in response to individual requirements for tightening force without using a plurality of tools and without the need to adjust the settings of a single tool, which is advantageous. A further advantage of the present invention is that when the composite washer is compressed into its secondary state, thereby indicating that a sufficient tightening force has been applied, the elastic portion is completely hidden on its side. This allows the user to unmistakably recognize that no further force is required, thus minimizing the risk of human error. In the secondary state of the composite washer, the upper and base portions do not necessarily need to be in direct contact to hide the elastic portion on the side of the composite washer. For example, the upper and base portions may overlap or be close enough to contact each other to hide the elastic portion so that it is not visible on the side of the composite washer. A further advantage of the present disclosure is that the elastic material visually indicates whether the tightening force has been loosened over time. A user visually inspecting the fastener immediately recognizes that the fastening element requires tightening by looking at the elastic portion on the side of the composite washer. Thus, the composite washer according to the present invention enables a quick and safe inspection of a large number of fasteners. Furthermore, the elastic material presses against the upper and base portions as a reaction when compressed. Thus, the composite washer applies an expansion force towards the fastener and the object to which the fastener is fastened. This increases the friction between the fastening element and the object to which the fastening element is fastened, which is advantageous for improving the resistance of the fastening element against rotation.This is further advantageous in reducing the risk of loosening of the fastening element due to vibrations by shifting the load applied to the fastening element. In this way, a composite washer is provided that exhibits the clamping force applied to the fastener and counteracts loosening of the fastener.

[0007] According to a further embodiment, the elastic part has a longitudinal extension along the axis from its upper part through an intermediate part to its lower part, and when the elastic part is not compressed, a first inner diameter at the upper part is different from a second inner diameter at the intermediate part. This provides that when the composite washer is compressed from its primary state to its secondary state, the elastic part can be smoothly compressed. Thereby, the risk that the elastic part undergoes undesired and potentially harmful oblique deformations during compression is significantly reduced. This is advantageous for extending the lifespan of the composite washer. Changing at least one of the first or second inner diameters of the upper and intermediate parts can further enable the compression resistance of the elastic part to be non-linear. For example, the amount of additional clamping force required to compress the composite washer by a specific distance can increase as the composite washer approaches its secondary state. This can be beneficial when fastening the fastener to prevent the fastened fastener from loosening.

[0008] According to a further embodiment, the first inner diameter is smaller than the second inner diameter. This provides that the intermediate part of the elastic part is thinner than at least one of the upper part and the lower part. This is advantageous for enabling uniform deformation of the elastic part when compressed by the upper and base parts. Also, the risk that the elastic part is damaged by pinching can be reduced.

[0009] According to a further embodiment, the elastic part comprises a groove extending circumferentially around the inner surface of the elastic part facing the axis. Thereby, the deformation of the elastic part is controlled by the groove, and thus the groove also serves to control the line of movement of the upper and base parts when the composite washer is compressed from its primary state to its secondary state. This is advantageous for promoting the alignment of the line of movement with the direction of the axis.

[0010] According to a further embodiment, the elastic part is in direct contact with the upper part and the base part. Thereby, the user can change the friction between the elastic part, the upper part, and the base part to a greater extent. If desired, the parts may be modified to have a high-friction connection. This improves the ability of the parts to withstand rotational movement relative to each other. This is advantageous in that it does not cause rotational wear of the components of the composite washer and thus extends its lifespan. Alternatively, the parts may be modified to have a low-friction connection to enable the parts to rotate around an axis relative to each other. Further, the elastic part may be directly adhered to at least one of the upper part and the base part, which is even more advantageous in preventing separation due to internal rotation.

[0011] According to a further embodiment, the elastic part is made of the material polyurethane. This offers a number of advantages. Polyurethane has great thermal stability. This is advantageous to ensure that the mechanical properties of the elastic part are not significantly affected by temperature during the expected outdoor temperature range. Thus, the user can rely on the accuracy of the composite washer to accurately indicate the required tension regardless of the outside air temperature. Polyurethane is even more advantageous as it has great durability against chemicals, oil, and water. Also, polyurethane is durable against wear and external impact and can withstand large forces without permanent deformation. Polyurethane further has the advantages of being easy to color and make transparent. It is also conceivable that the elastic material is EPDM rubber. Using EPDM rubber is advantageous as it has great durability against UV irradiation, chemicals, and water. EPDM rubber is even more advantageous as it has great shock-absorbing properties. Also, EPDM rubber can be suitably used for composite washers used outdoors because the change due to temperature is very small.

[0012] According to a further embodiment, the elastic part has a visually different color, for example red or green. This facilitates the user's visual recognition of the elastic part. This is advantageous for ensuring the visual load indication function of the composite washer. It is advantageous to use colors associated with meaning, for example, red is used to indicate danger and green is used to indicate safety.

[0013] According to a further embodiment, the elastic part is fluorescent. This provides that the elastic part emits light absorbed from a light source or any other electromagnetic radiation. This is advantageous for facilitating the user's determination of whether the elastic part is visible on the side of the composite washer. This is particularly advantageous at night since the visibility of fluorescence is enhanced in the dark.

[0014] According to a further embodiment, the elastic part is adhered to the upper part and the base part. This provides for easy assembly of the composite washer. It is further advantageous to form a uniform contact surface between the elastic part, the upper part, and the base part.

[0015] According to a further embodiment, the upper part comprises an outer upper wall part extending circumferentially around the axis, where the outer upper wall part has a longitudinal extension towards the base part, and where the base part comprises an outer base wall part extending circumferentially around the axis, and where the outer base wall part has a longitudinal extension towards the upper part. Thereby, the deformation of the radially outer end portion of the elastic part can be suppressed by the upper wall part and the base wall part. The upper wall part and the base wall part can also function as a protective surface of the composite washer.

[0016] According to a further embodiment, the outer upper wall portion and the outer base wall portion are arranged to be separated in a primary state and in contact in a secondary state. Thereby, the upper wall portion and the base wall portion can stop the compression of the composite washer. This is advantageous for preventing the elastic portion from being subjected to an excessively high compressive force that could lead to damage. The composite washer is preferably designed such that when the upper wall portion and the base wall portion are arranged in contact, a sufficient amount of tightening is applied. Further, when the composite washer is compressed to its secondary state, the composite washer is stationary, so the user applying the tightening force immediately senses that the compression of the composite washer is being impeded. Thereby, the user knows that a sufficient amount of force has been applied. This is advantageous for avoiding applying an excessive tightening force to the fastener.

[0017] According to a further embodiment, the outer upper wall portion is arranged on the outer periphery of the upper part, where the outer base wall portion is arranged on the outer periphery of the base portion.

[0018] According to a further embodiment, the upper part comprises an upper engaging part that engages with the elastic part so that the connection between the elastic part and the upper part is maintained, where the base part comprises a base engaging part that engages with the elastic part so that the connection between the elastic part and the base part is maintained. This provides that the upper part, the elastic part, and the base part do not need to be attached to each other by means other than the upper engaging part and the base engaging part. To enable the upper coupling part and the base coupling part to couple with the elastic part, it is preferable that the elastic part has a first inner diameter at its upper part and a third inner diameter at its lower part that are smaller than the second inner diameter of its middle part. The elastic part may be, for example, C-shaped. Also, an elastic member with a C-shaped cross-section may be arranged such that the upper engaging part engages with the upper part of the C-shaped cross-section and the base engaging part engages with the lower part of the C-shaped cross-section. The upper engaging part and the base engaging part preferably engage with the elastic part. For example, the connection between the upper part, the elastic part, and the base part is maintained when using a composite washer according to its intended use. Further, this connection is preferably not so strong as to prevent the user from disassembling the composite washer if desired. If the upper part, the base part, and the elastic part are attached to each other only by the upper engaging part and the base engaging part, it may further be considered desirable to enable the upper part, the base part, and the elastic part to rotate independently of each other about the axis. To facilitate this, the surfaces of the upper part and the base part that are in direct contact with the elastic part when the composite washer is in its primary or secondary state are preferably smooth to create a low-friction connection between the surface and the elastic part. This is advantageous for increasing the clamping force of the fastener against the applied tightening force.

[0019] According to a further embodiment, the upper engagement portion comprises a first inclined surface extending circumferentially around the axis, where the first inclined surface faces away from the axis towards the base portion, and where the base engagement portion comprises a second inclined surface extending circumferentially around the axis, where the second inclined surface faces away from the axis towards the upper portion. This enables easy assembly of the composite washer. The first and second inclined surfaces allow the elastic part to slide into its intended position where it engages with the upper engagement portion and the base engagement portion with minimal force. The upper and base engagement portions further ensure that the elastic part remains in its intended position.

[0020] According to a further embodiment, the upper part comprises a first contact portion and the base part comprises a second contact portion, where the first contact portion is in direct contact with the second contact portion. Thereby, in the primary and secondary states of the composite washer, the upper and base parts are in contact. Thereby, the upper part can restrain the base part in at least one direction. This is advantageous for avoiding unwanted displacement of the base part relative to the upper part.

[0021] According to a further embodiment, the first contact portion restricts the second contact portion from moving laterally within a plane perpendicular to the axis. This provides that the upper part suppresses the movement of the base part within a plane perpendicular to the axis. This is advantageous for ensuring that the upper and base parts are displaced only along the direction of the axis relative to each other, thus avoiding oblique loads and the like.

[0022] According to a further embodiment, the first contact portion comprises a first locking element and the second contact portion comprises a second locking element, where the first locking element is engaged with the second locking element such that the connection between the first contact portion and the second contact portion is maintained.

[0023] As a result, the upper part, the elastic part, and the base part can remain connected by the first locking element and the second locking element. Furthermore, the composite washer may advantageously be assembled by compressing the upper part axially towards the base part. The first contact part and the second contact part are preferably connected with a force high enough to maintain the connection of the composite washer during its intended use, while the force is low enough to allow for the disassembly of the washer if desired.

[0024] According to a further embodiment, at least one of the upper part and the base part comprises an inner recess on the inner surface that contacts the elastic part. This improves the ability to apply an adhesive to the upper part and the base part. The inner recess is advantageous as it allows more adhesive to be applied between the upper part or the base part and the elastic part. The inner recesses are further advantageous as they provide an irregular surface that can improve the bonding ability of the adhesive towards the upper part or the base part.

[0025] According to a further embodiment, at least one of the upper part and the base part is perpendicular to the axis and has an outer surface facing away from the elastic part, where the outer surface comprises an outer recess. This provides an improved ability to withstand rotational movement, which is advantageous as the upper part or the base part can lock against either a fastening element (nut, bolt, screw) or the object to which the fastening tool is fastened via the outer recess. This prevents the rotational movement of the composite washer relative to any of the above objects. This is advantageous for preventing loosening of the fastening tool.

[0026] According to a further embodiment, the outer recess extends in the radial direction of the axis. This causes the outer recess to be inclined laterally in the rotational direction of the composite washer, which is advantageous for providing rotational resistance against the fastening tool or the object to which the fastening tool is fastened.

[0027] According to a further embodiment, there is provided a system for fixing a fence post to a building structure, the system comprising a composite washer. Using the composite washer as a load indicator for the fastener for the fence of the building structure is particularly advantageous because the consequences of an inadvertently loosened fastener are severe. The composite washer indicates by visual inspection whether the applied tightening force is sufficient for a secure fastening of the fence. Since the fastener to which the composite washer is applied can be arranged in an exposed position, the composite washer enabling visual inspection is further advantageous for the fence on the building structure. Thus, it is difficult or dangerous to reach that position. Thereby, by using the composite washer and the load indicator, there is no need to apply torque to the fastener for inspection.

[0028] According to a further embodiment, the system further comprises a clamp for clamping the structure with a clamping force, and the composite washer is arranged to be compressed by the clamping force. This provides that the composite washer can indicate the clamping force of the clamp. Since the composite washer is always compressed when the clamp is clamping the structure, it is further advantageous to arrange the composite washer so that it is compressed by the clamping force. Thus, the user is assured that the composite washer has not been forgotten and is automatically reminded by the force indicating composite washer that a sufficient amount of clamping force has been applied. Further, due to the expansion effect when the composite washer is compressed, the clamp is automatically prevented from loosening.

[0029] According to a further embodiment, the system further comprises a wing nut arranged to compress the composite washer and the clamp. By providing the wing nut, the user can, for example, use a hammer to apply tension to the wing nut, thereby applying tension to the system for fixing the post. This is advantageous because, thanks to the composite washer, the user can apply a large force while still ensuring that the applied force is within the desired tension range.

[0030] According to a further embodiment, the composite washer is used as a safety load indicator. This provides that the visual indicator of the composite washer can be used to inform that the load is within the range of the lifting device. This is advantageous in preventing overloading of the lift, i.e., when the load is greater than the lifting capacity of the lift.

[0031] According to a further embodiment, a system for indicating a safe lifting force comprising a composite washer is provided. According to a further embodiment, the system for indicating a safe lifting force further comprises a lower lifting pin having a lower flat portion and a lifting portion, and an upper lifting pin having an upper flat portion and a carrier portion, wherein the lifting portion is arranged to be lifted and the carrier portion is arranged to carry the load, and wherein the washer is arranged between the lifting portion and the carrier portion such that when the system is lifted and carries the load, the lower flat portion and the upper flat portion compress along the axis of the composite washer.

[0032] According to a further embodiment, the lower flat portion comprises a lower aperture and the upper flat portion comprises an upper aperture, wherein the carrier portion and the lifting portion are arranged to extend through the lower aperture and the upper aperture, respectively. This provides a system that can be used in combination with a lifting device for indicating a safe lifting force. By providing apertures in the upper and lower lifting pins, the sides of the composite washer can be fully visible to the user. This is advantageous in allowing the user to see as clearly as possible the load indication provided by the composite washer. The components of the composite washer are preferably adapted such that the load is less than the capacity of the lifting device unless the composite washer reaches its secondary state.

[0033] It should be further noted that the concept of the present invention relates to all possible combinations of features unless otherwise specified.

[0034] The present disclosure will be described in the following illustrative and non-limiting detailed description of exemplary embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

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[0036] All the drawings are schematic and not necessarily to scale. Generally, only the parts necessary to explain the present disclosure are shown, and other parts are omitted or merely suggested. Throughout the drawings, the same reference numerals indicate the same or essentially the same features.

Embodiments for Carrying Out the Invention

[0037] For simplicity, structural details that are considered to be basic knowledge of those skilled in the art and that do not contribute to explaining the essence of the concept of the present invention are omitted in the following description.

[0038] A first exemplary embodiment of the composite washer 100 will be described with reference to FIGS. 1, 2a, 2b, and 3. FIG. 1 shows a composite washer 100 comprising an upper part 120, an elastic part 130, and a base part 140. The upper part 120 has a circumferential extension around the axis A. The elastic part 130 has a circumferential extension around the axis A. The base part 140 has a circumferential extension around the axis A. The upper part 120, the elastic part 130, and the base part 140 are connected to each other, where the elastic part 130 is disposed between the upper part 120 and the base part 140, and there is a central opening 102 along the axis A passing through the upper part 120, the elastic part 130, and the base part 140. The central opening 102 has a diameter large enough so that a part of a desired member, such as a shank of a fastener, can extend through the central opening 102. In the disclosed embodiment, the upper part 120 comprises an outer upper wall part 121 and an inner upper wall part 128 that extend circumferentially around the axis A. The outer upper wall part 121 and the inner upper wall part 128 have a longitudinal extension parallel to the axis A towards the base part 140. The outer upper wall part 121 is further disposed on the outer circumference of the upper part 120, and the inner upper wall part 128 is disposed on the inner circumference of the upper part 120. The base part 140 comprises an outer base wall part 141 and an inner base wall part 148 that extend circumferentially around the axis A. The outer base wall part 141 and the inner base wall part 148 have a longitudinal extension parallel to the axis A towards the upper part 120. The outer base wall part 141 is disposed on the outer circumference of the base part 140, and the inner base wall part 148 is disposed on the inner circumference of the base part 140. The upper part 120 and the base part 140 are preferably made of a metal such as steel or aluminum. However, it is contemplated that the upper part 120 or the base part 140 can be made from any rigid durable material. The elastic part 130 is made of an elastic material, preferably polyurethane. Also, the elastic part 130 can be considered to be made of, for example, EPDM rubber. The composite washer 100 of FIG. 1 is shown in its primary state S1. In the illustrated embodiment, the elastic part 130 is adhered to the upper part 120 and the base part 140. When the composite washer 100 is in its primary state S1, the upper part 120 is not in direct contact with the base part 140. Thus, the elastic part 130 can be seen at the side 104 of the composite washer 100.The elastic part 130 is preferably colored in a visually different color, such as red or green. Alternatively, the elastic part 130 may be fluorescent. FIGS. 2a and 2b respectively show the primary state S1 and the secondary state S2 of the composite washer 100. The composite washer 100 is arranged to be in its primary state S1 when not compressed. In the primary state S1, the upper part 120 and the base part 140 are separated by the elastic part 130. Therefore, the elastic part 130 is visible on the side surface of the composite washer 100. The composite washer 100 is arranged to be compressed along the axis A such that the composite washer 100 is compressed into its secondary state S2. When the composite washer 100 is in its secondary state S2, the elastic part 130 is hidden by the upper part 120 and the base part 140 at its side surface 104. In the present embodiment, the composite washer 100 is further configured such that the outer upper wall part 121 and the outer base wall part 141 are separated in the primary state S1 and in contact in the secondary state S2. As seen in FIG. 1, the inner upper wall part 128 and the inner base wall part 148 are similarly arranged to be separated in the primary state S1 and in contact in the secondary state S2. FIG. 3 shows a cross-section A-A of FIG. 1 of the composite washer 100 in its primary state S1. The elastic part 130 has a longitudinal extension parallel to the direction of the axis A. In the illustrated embodiment, the elastic part 130 has a rectangular cross-section. The elastic part 130 is in direct contact with the upper part 120 and the base part 140.

[0039] Seven further exemplary embodiments of the composite washers 200, 300, 400, 500, 600, 700, and 800 will be described with reference to FIGS. 4 to 10. All of the seven exemplary embodiments have a structure basically similar to that of the first exemplary embodiment of the composite washer 100 described with reference to FIGS. 1, 2a, 2b, and 3. The detailed nomenclature is the same for all seven further embodiments, except for the first number of the number referring to each exemplary embodiment of the composite washer.

[0040] Next, with reference to FIG. 4, a second exemplary embodiment of the composite washer 200 will be described. FIG. 4 shows a cross-section of the composite washer 200, where the washer is in its primary state S1. The elastic portion 230 has a longitudinal extension in the direction of the axis A from the upper portion 231 through the intermediate portion 232 to the lower portion 233. The elastic portion 230 has a first inner diameter D1 in the upper portion 231 that is smaller than a second inner diameter D2 in the intermediate portion 232, where a third inner diameter D3 is smaller than the second inner diameter D2. Accordingly, the elastic portion 230 is provided with a concave inner surface.

[0041] A third exemplary embodiment of the composite washer 300 will be described with reference to FIG. 5. FIG. 5 shows the composite washer 300 where the washer is in its primary state S1. In the illustrated embodiment, the elastic portion 330 includes a groove 334 having a circumferential extension around the inner surface of the elastic portion 330 facing the axis A. The groove 334 has a concave shape positioned on the elastic portion between the inner upper wall portion 328 and the inner base wall portion 348 in the illustrated embodiment.

[0042] Next, with reference to FIG. 6, a fourth exemplary embodiment of the composite washer 400 will be described. FIG. 6 shows the composite washer 400 with the washer in its primary state S1. In the illustrated embodiment, the upper part 420 includes an upper engagement portion 422. The upper engagement portion 422 is engaged with the elastic portion 430 so that the connection between the elastic portion 430 and the upper part 420 is maintained. More specifically, the upper engagement portion 422 projects radially from the inner upper wall portion 428 in a direction away from the axis A at its end closest to the base portion 440. In other words, the upper engagement portion 422 forms a lip extending radially outward from the inner upper wall portion 428. The upper engagement portion 422 has a circumferential extension around the axis A. The upper engagement portion 422 projects away from the axis A at a distance long enough to engage with the elastic portion 430 to maintain the connection between the upper part 420 and the elastic portion 430. Further, the base portion 440 includes a base engagement portion 442. The base engagement portion 442 is engaged with the elastic portion 430 so that the connection between the elastic portion 430 and the base portion 440 is maintained. More specifically, the base engagement portion 442 projects radially from the inner base wall portion 448 in a direction away from the axis A at its end closest to the upper part 420. In other words, the base engagement portion 442 forms a lip extending radially outward from the inner base wall portion 448. The base engagement portion 442 has a circumferential extension around the axis A. The base engagement portion 442 projects away from the axis A at a distance long enough to engage with the elastic portion 430 to maintain the connection between the base portion 440 and the elastic portion 430. In this embodiment, the elastic portion 430 has a C-shaped radial cross-section. This is to improve the ability of the upper engagement portion 422 and the base engagement portion 442 to engage with the elastic portion 430. As shown in FIG. 6, the upper engagement portion 422 engages with the upper part of the C-shaped cross-section of the elastic portion 430, and the base engagement portion 442 engages with the lower part of the C-shaped cross-section of the elastic portion 430. The interconnection of the upper part 420, the elastic portion 430, and the base portion 440 is preferably high enough to maintain the interconnection when using the composite washer 400 according to its intended use, and preferably low enough to allow the user to disassemble the composite washer 400 if desired.In the present embodiment, the upper engagement portion 422 includes a first inclined surface 423 that extends circumferentially around the axis A and faces the base portion 440 away from the axis A. Further, the base engagement portion 442 includes a second inclined surface 443 that extends circumferentially around the axis A and faces the upper portion 420 away from the axis A.

[0043] A fifth exemplary embodiment of the composite washer 500 will be described with reference to FIG. 7. FIG. 7 shows the composite washer 500 with the washer in its primary state S1. In the illustrated embodiment, the upper portion 520 includes a first contact portion 525, and the base portion 540 includes a second contact portion 545. The first contact portion 525 is in direct contact with the second contact portion 545 in the primary state S1 of the composite washer 500 and in the secondary state S2 of the composite washer. In the illustrated embodiment, the first contact portion 525 has a circumferential extension around the axis A and a longitudinal extension parallel to the axis A toward the base portion 540. The second contact portion 545 has a circumferential extension around the axis A and the first contact portion 525 and a longitudinal extension parallel to the axis A toward the upper portion 520, and a part of the first contact portion 525 and a part of the second contact portion 545 extend parallel to each other. The first contact portion 525 and the second contact portion 545 are engaged with each other so as to restrict relative movement between them in a plane perpendicular to the axis A. In other words, the first contact portion 525 and the second contact portion 545 are arranged substantially concentrically with each other. In the illustrated embodiment, the elastic portion 530 has a fourth inner diameter D4 at the upper portion 531 of the elastic portion 530 that is larger than a fifth inner diameter D5 at the intermediate portion 532 of the elastic portion 530.

[0044] A sixth exemplary embodiment of the composite washer 600 will be described with reference to FIG. 8. FIG. 8 shows the composite washer 600 with the washer in its primary state S1. In contrast to the composite washer shown in FIG. 7, the first contact portion 625 has a circumferential extension around the second contact portion 645. The first contact portion 625 includes a first locking element 624 that extends circumferentially around the axis A. In the illustrated embodiment, the first locking element 624 includes a circumferential surface having a sixth inner diameter D6 that is slightly smaller than a seventh inner diameter D7 of the remainder of the first contact portion 625. The second contact portion 645 includes a second locking element 644. The second locking element 644 extends circumferentially around the axis A and is arranged to have an outer diameter larger than the sixth inner diameter D6 of the first locking element 624. The first locking element 624 is arranged to engage with the second locking element 644 so that the connection between the first contact portion 625 and the second contact portion 645 is maintained when the composite washer 600 is in its primary state S1. Thereby, the second locking element 644 abuts against the first locking element 624 to suppress the movement of the base portion 640 away from the upper portion 620.

[0045] Next, a seventh exemplary embodiment of the composite washer 700 will be described with reference to FIG. 9. FIG. 9 shows the composite washer 700 according to a further embodiment. The upper portion 720 includes an inner recess (not shown) on the inner surface of the upper portion 720, and this inner surface is perpendicular to the axis A and in contact with the elastic portion 730. The base portion 740 includes an inner recess (not shown) on the inner surface of the base portion 740, and its inner surface is perpendicular to the axis A and in contact with the elastic portion 730. The inner recess of the upper portion and the inner recess of the base portion 740 extend radially from the axis A and are evenly distributed. In the illustrated embodiment, the upper portion 720 is further provided with an outer surface facing away from the elastic portion 730 and perpendicular to the axis A, where the outer surface includes an outer recess 727. The outer recess 727 extends in the radial direction of the axis A. The base portion 740 is perpendicular to the axis A and further includes an outer surface facing away from the elastic portion 730 and includes a similar outer recess (not shown) extending in the radial direction of the axis A.

[0046] An eighth exemplary embodiment of the composite washer 800 will be described with reference to FIG. 10. FIG. 10 shows the composite washer 800 with the washer in its primary state S1. The composite washer 800 includes an upper part 820, an elastic part 830, and a base part 840. The upper part 820 includes an inner upper wall part 828 and an upper engaging part. The inner upper wall part 828 and the upper engaging part 822 have functions similar to those of the inner upper wall part 428 and the upper engaging part 422 shown in the fourth exemplary embodiment shown in FIG. 6. The upper engaging part 822 is engaged with the elastic part 830 so that the connection between the elastic part 830 and the upper part 820 is maintained. More specifically, the upper engaging portion 822 radially projects in a direction away from the axis A at its end closest to the base portion 840, starting from the inner upper wall portion 828. The base portion 840 includes an inner base wall portion 848 and a base engaging portion 842. The inner base wall part 848 and the base engaging part 842 have functions similar to those of the inner base wall part 448 and the base engaging part 442 shown in the fourth exemplary embodiment shown in FIG. 6. The base engaging part 842 is engaged with the elastic part 830 so that the connection between the elastic part 830 and the base part 840 is maintained. More specifically, the base engaging portion 842 radially projects in a direction away from the axis A at its end closest to the upper part 820, starting from the inner base wall portion 848. In this embodiment, the upper engaging part 822 includes a first inclined surface 823 that extends circumferentially around the axis A and faces the base part 840 away from the axis A. The base engaging part 842 includes a second inclined surface 843 that extends circumferentially around the axis A and faces the upper part 820 away from the axis A. The upper engaging portion 822 includes a third inclined surface 829, and the third inclined surface 829 extends circumferentially around the axis A and faces in a direction away from the axis A and away from the base portion 840. The base engaging part 842 includes a fourth inclined surface 849 that extends circumferentially around the axis A and faces in a direction away from the axis A and away from the upper part 820. The third and fourth inclined surfaces are engaged with the elastic part 830 and have corresponding inclined surface portions.

[0047] Two exemplary embodiments of systems 900, 1000 for fixing a fence post to a building structure will be described with reference to FIGS. 11 through 13.

[0048] A first exemplary embodiment of a system 900 for fixing a fence post to a building structure will be described with reference to FIG. 11. FIG. 11 shows a system 900 including a composite washer 100 for fixing a fence post to a building structure. The system 900 includes an anchor structure 903 and a fastener 904 arranged to fasten the anchor structure 903 to a building structure B. In the illustrated embodiment, the fastener 904 is a concrete bolt. The composite washer 100 is disposed between the fastener 904 and the anchor structure 903 such that it is compressed when the anchor structure 903 is fixed to the building structure B by the fastener 904. The shank of the fastener 904 extends through the central opening 102 of the composite washer 100. The composite washer 100 is further arranged to be compressed to its secondary state S2 when the required tension is applied to the fastener 904. It is contemplated that the fastener may be a type of fastener other than a bolt, such as a screw or a nut.

[0049] A second exemplary embodiment of system 1000 for fixing a fence post to a building structure will be described with reference to FIGS. 12 and 13. FIGS. 12 and 13 show system 1000 for fixing a fence post to a building structure according to a further embodiment. System 1000 includes a clamp 1001 for clamping the structure of the building structure with a clamping force, and a composite washer 100. The composite washer 100 is arranged to be compressed by the clamping force. The system 1000 for fixing the fence post further includes a wing nut 1002 arranged to compress the composite washer 100 while pulling the clamp 1001. The clamp 1001 can further include a threaded rod 1005, a fixed clamp member 1006 attached to one end of the threaded rod 1005, and a movable clamp member 1007 arranged on the threaded rod 1003 so as to be movable along the threaded rod 1005. The wing nut 1002 is threadedly engaged with the threaded rod 1005. When the user places the clamp members 1006, 1007 in contact with both sides of a structure such as the floor to place the clamp on the structure and tightens the wing nut 1002, the composite washer 100 is compressed. When the elastic part between the upper part and the base part of the composite washer 100 can no longer be seen, a sufficient clamping force has been reached.

[0050] Figures 14 through 15 show a system 1100 for demonstrating a safe lifting force with a composite washer 100. The system 1100 for demonstrating a safe lifting force includes a lower lifting pin 1110 and an upper lifting pin 1120. An exploded view of the system 1100 is shown in FIG. 14. The lower lifting pin 1110 includes a circular plate-shaped lower flat portion 1111 and a lifting portion 1112 connected to the center of the lower flat portion 1111, and the lifting portion 1112 protrudes in a direction perpendicular to the flat surface of the lower flat portion 1111. The lifting portion 1112 has an opening at its end, which is the end farthest from the lower flat portion 1111. Further, the lower flat portion 1111 includes two lower apertures 1113, one on each side of the lifting portion 1112, and they are equidistant from the center of the lower flat portion 1111. The system for demonstrating the safe lifting force 6 further includes an upper lifting pin 1120. The upper lifting pin 1120 includes an upper flat portion 1121 formed as a circular plate and a carrier portion 1122. The carrier portion includes two arms, which are connected to the upper flat portion 1121 and protrude in a vertical direction from the circular plate surface of the upper flat portion 1121. Each of the two arms of the carrier portion 1122 has an opening for attaching a load at the end farthest from the upper flat portion 1121. The upper flat portion 1121 has an upper aperture 1123 at its center. The system 1100 for demonstrating a safe lifting force is assembled such that the composite washer 100 is attached to the lower lifting pin 1110 so that the lifting portion 1112 extends through the opening of the composite washer 100. The upper lifting pin 1120 is attached together with the lower lifting pin 1110 and the composite washer 100 such that the lifting portion 1112 extends through the upper aperture 1123 of the upper lifting pin 1120 and the two arms of the carrier portion 1122 extend through the openings of the composite washer 100 and both apertures 1113 of the lower lifting pin. A load is attached to the upper lifting pin 1120.System 1100 for indicating a safe lifting force may then carry a load lifted into the opening of the lower lifting pin 1110 and attached to the two openings of the upper lifting pin 1120 by a lifting device. When the system 1100 for indicating a safe lifting force is lifted, the lower flat portion 1111 and the upper flat portion 1121 compress the composite washer 100 with a force equal to the lifting force. The composite washer 100 is preferably modified so as not to be completely compressed to reach the secondary state S2 as long as the lifting force is within the safe load of the lifting device. Thus, the user using the system has a visual indicator indicating whether the lifting force is within the safety limit of the lifting device. The elastic portion 130 of the composite washer 100 is preferably colored in a visually different color such as green.

[0051] Although the present disclosure has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered as illustrative or exemplary and not restrictive. The present disclosure is not limited to the disclosed embodiments.

[0052] Other variations to the disclosed embodiments can be understood and achieved by those skilled in the art in practicing the claimed invention, from a consideration of the drawings, the disclosure, and the appended claims. In the claims, the term "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 measures cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope.

Claims

Claim 1 A composite washer for force indication and prevention of loosening of fasteners, comprising: an upper part having a circumferential extension around the axis; an elastic part having a circumferential extension around the axis; a base part having a circumferential extension around the axis, wherein the upper part, the elastic part, and the base part are connected to each other, the elastic part is disposed between the upper part and the base part, and there is a central opening having an extension along the axis over the entire upper part, the elastic part, and the base part, the composite washer is disposed in a primary state in which the elastic part is visible from its side, the composite washer is disposed in a secondary state in which the elastic part is compressed by the upper part and the base part such that the side surface of the elastic part is hidden by at least one of the upper part and the base part. Claim 2 The composite washer according to claim 1, wherein the elastic part has a longitudinal extension along the axis from its upper part through an intermediate part to its lower part, and when the elastic part is not compressed, a first inner diameter at the upper part is different from a second inner diameter at the intermediate part. Claim 3 The composite washer according to claim 2, wherein the first inner diameter is smaller than the second inner diameter. Claim 4 The composite washer according to any one of claims 1 to 3, wherein the elastic part comprises a groove extending circumferentially around an inner surface of the elastic part facing the axis. Claim 5 The composite washer according to any one of claims 1 to 4, wherein the elastic part is in direct contact with the upper part and the base part. Claim 6 The composite washer according to any one of claims 1 to 5, wherein the elastic part is made of a polyurethane material. Claim 7 The composite washer according to any one of claims 1 to 6, wherein the elastic part has a visually different color, such as red or green. Claim 8 The composite washer according to any one of claims 1 to 7, wherein the elastic part is fluorescent. Claim 9 The composite washer according to any one of claims 1 to 8, wherein the elastic part is adhered to the upper part and the base part. Claim 10 The upper part includes an outer upper wall portion that extends circumferentially around the axis, the outer upper wall portion has a longitudinal extension portion that faces the base portion, the base portion includes an outer base wall portion that extends circumferentially around the axis, and the outer base wall portion has a longitudinal extension portion that faces the upper part. The composite washer according to any one of claims 1 to 9.

11. The composite washer according to claim 10, wherein the outer upper wall portion and the outer base wall portion are arranged to be separated in the primary state and to contact each other in the secondary state.

12. The composite washer according to claim 11, wherein the outer upper wall portion is arranged on the outer periphery of the upper part, and the outer base wall portion is arranged on the outer periphery of the base portion.

13. The upper part includes an upper engaging portion that engages with the elastic portion so that the connection between the elastic portion and the upper part is maintained, and the base portion includes a base engaging portion that engages with the elastic portion so that the connection between the elastic portion and the base portion is maintained. The composite washer according to any one of claims 1 to 12.

14. The upper engaging portion includes a first inclined surface that extends circumferentially around the axis, the first inclined surface faces away from the axis and toward the base portion, the base engaging portion includes a second inclined surface that extends circumferentially around the axis, and the second inclined surface faces away from the axis and toward the upper part. The composite washer according to claim 13.

15. The composite washer according to any one of claims 1 to 14, wherein the upper part includes a first contact portion, the base portion includes a second contact portion, and the first contact portion is in direct contact with the second contact portion.

16. The composite washer according to claim 15, wherein the first contact portion restricts lateral movement of the second contact portion within a plane perpendicular to the axis.

17. The composite washer according to claim 15 or 16, wherein the first contact portion includes a first locking element, the second contact portion includes a second locking element, and the first locking element engages with the second locking element so that the connection between the first contact portion and the second contact portion is maintained.

18. The composite washer according to any one of claims 1 to 17, wherein at least one of the upper part and the base portion includes an inner concave portion on an inner surface that contacts the elastic portion.

19. At least one of the upper part and the base part is perpendicular to the axis and has an outer surface facing away from the elastic part, and the outer surface has an outer recess. The composite washer according to any one of claims 1 to 18.

20. The outer recess extends in the radial direction of the axis. The composite washer according to claim 19.

21. A system for fixing a fence post provided with the composite washer according to any one of claims 1 to 20 to a building structure.

22. The system further includes a clamp for clamping the structure with a clamping force, and the composite washer is arranged to be compressed by the clamping force. A system for fixing a fence post according to claim 21 to a building structure.

23. The system according to claim 21 or 22, further comprising a wing nut arranged to compress the composite washer and the clamp.

24. The composite washer according to any one of claims 1 to 19, which is used as an indicator of a safe lifting force.

25. A system for indicating a safe lifting force, comprising the composite washer according to any one of claims 1 to 19.

26. A lower lifting pin having a lower flat part and a lifting part, An upper lifting pin having an upper flat part and a carrier part, the lifting part is arranged to be lifted, the carrier part is arranged to carry a load, The washer is arranged between the lifting part and the carrier part such that when the system is lifted and carries a load, the lower flat part and the upper flat part compress the composite washer along the axis. A system for indicating a safe lifting force according to claim 25.

27. The lower flat part has a lower aperture, the upper flat part has an upper aperture, and the carrier part and the lifting part are arranged to extend through the lower aperture and the upper aperture, respectively. A system for indicating a safe lifting force according to claim 26.

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