AU2011200160A1 - Calibration Device - Google Patents

Abstract

Abstract A calibration device is provided for calibrating weight measurement devices. According to at least one embodiment, the device comprises a base, a lever 5 pivotably attached to the base, an adjustment member also pivotably attached to the base, an actuation member engaged with the adjustment member, a load cell, and a connector for attaching the calibration device to a load connecting member, wherein at least a portion of the adjustment member shaft is threaded and wherein the lever comprises a coupling having an aperture with a threaded interior for engagement 10 with the threaded portion of the adjustment member such that rotation of the adjustment member causes the lever to move along the adjustment member shaft. The device therefore simulates a weight. Also provided is an anchor member for engaging the calibration device with a mounting surface, and a method for calibrating a weighing device.

Description

CALIBRATION DEVICE 5 Field of the Invention The invention relates to a calibration device and a method for calibrating measurement devices, particularly measurement devices that are either permanently mounted at a location that is difficult to access; or that are of high capacity and where 10 calibrated weights can not be easily placed on the measurement devices, or not enough calibrated weights can be placed on the measurement devices to achieve capacity. Background 15 It is commonplace for many industries to measure the weight of a material. For example, it may be important to obtain the correct weight when filling a package needing to be a particular weight, when loading a truck without exceeding the load limit, or when adding the correct amount of material to a mixture for a recipe. Many 20 industries in which the weighing of product is commonplace, and where the correct weight is imperative, require the measurement devices used to weigh the material to be regularly checked and calibrated. To comply with certain industry regulations, it is common for companies to engage 25 external registered calibration organisations to carry out independent certification tests as part of their compliance. In addition, they also have to carry out their own calibration checks periodically throughout the year to ensure that the manner of weighing of material that they are carrying out is within acceptable industry parameters and complies with their own registration. Therefore, in many situations, 30 their operators are required to access awkward and often dangerous areas where the measurement devices are located. Currently, the operators must carry test weights to these areas in order to test whether the measurement device is correct and to calibrate the device using the substitution method, which means that test weights have to be added and removed many times to complete the test. Sometimes the 35 measurement devices can be high up and/or in confined spaces, which makes it both difficult and dangerous for an operator to transport test weights to the measurement device. As a result, operator injuries are not uncommon. 1 In situations where the measurement device is used to weigh material held within a hopper, the use of test weights is difficult and a substitution method of calibration is often required. In these cases, certified test weights are placed on to the hopper and 5 a weight reading taken, the weights are then removed and a known weight of the material itself, or water is added to the hopper and the measurement device is then read. The weights are then added again and another reading taken and the entire process is repeated until the capacity of the device is reached. The readings are documented and the results are checked to assess whether the measurement device 10 is recording the correct weight of the material. In certain operations water can be used, but it washes out some of the material that was initially within the hopper and the water becomes contaminated. The disposal of this waste water then becomes an issue for the owner of the site. In other cases water can not be used if the material being weighed is a powder and the water would degrade the product and make the 15 hopper inoperable. Furthermore, due to the time consuming nature of calibrating measurement devices, it is commonplace for calibration to take place outside normal operating hours. This means that if the material to be weighed is cement for example, and the hopper is 20 filled with cement for calibration, the cement will need to be discarded as waste so that it does not solidify inside the hopper in the interim period before the business starts operating again. Needless to say, the disposal of material as waste is costly. It is an object of the present invention to go at least some way towards overcoming 25 the above described disadvantages of the prior art or to at least provide the public with a useful alternative. Summary 30 In one aspect, the invention provides a calibration device for calibrating weight measurement apparatuses, the device comprising: a base having a first end and a second end; a lever having a first end and a second end, the first end of the lever being pivotably attached to the base at or near the first end of the base; 35 an adjustment member in the form of a shaft having a first end and a second end, the first end of the adjustment member being pivotably attached to the base at or near the second end of the base; 2 a first actuation member that is engaged with the adjustment member for rotating the adjustment member; a load cell in communication with the lever so as to sense vertical movement of the lever, the load cell being connected to a digital display for displaying a load 5 calculated by the load cell; and a connector for attaching the calibration device to a load connecting member. In this aspect of the invention, at least a portion of the adjustment member shaft is threaded and the lever comprises a coupling, at or near the second end of the lever, the coupling having an aperture with a threaded interior for engagement with the 10 threaded portion of the adjustment member such that rotation of the adjustment member causes the lever to move along the adjustment member shaft. Preferably, the lever comprises a pair of support arms positioned adjacent to each other in a spaced apart relationship. In this form, the coupling is located between the 15 support arms and is pivotably attached to each support arm. The first actuation member may be in the form of a handle attached to the adjustment member, or it may be a motor. Alternatively, the calibration device may comprise both a handle and a motor as actuation members. 20 Preferably, the base of the calibration device is substantially planar. In another aspect, the invention provides an anchor member adapted to be used with the calibration device of the invention. The anchor member comprises a base 25 adapted to be attached to a mounting surface. The base also comprises a pair of anchor rails substantially spaced apart from each other, each anchor rail also being spaced apart from the base of the anchor member by at least one spacer. The spacers and anchor rails are arranged so that a portion of each anchor rail projects beyond the respective spacer toward the opposing anchor rail to form an 30 overhanging flange. The base of the anchor member, the spacers and the projecting anchor rails define a receiving cavity adapted to receive at least a portion of the base of the calibration device therein. Preferably, each spacer is substantially parallel to the opposing spacer and each 35 anchor rail is substantially parallel to the other. 3 In another aspect, the invention provides an infill for insertion into the receiving cavity of the anchor member of the invention. The infill comprises a base and an upper portion projecting from the base, the base and upper portion being profiled to fit snugly within the receiving cavity of the anchor member. 5 In yet another aspect, the invention provides a kit of parts comprising a calibration device according to invention and further comprising an anchor member according to the invention. 10 Preferably, the kit of parts further comprises at least one load connecting member for connecting the calibration device to a structure to which a load is to be applied. The load connecting member(s) may be a chain, rod, or the like. Most preferably, the kit of parts further comprises an infill according to the invention. 15 In yet another aspect, the invention provides a method for calibrating a weighing device for weighing load applied to a structure, the method comprising the steps of: a) providing a calibration device according to the invention; b) attaching the calibration device to a mounting surface below the structure; 20 c) attaching a connecting member to the calibration device and to the structure so that the connecting member is under tension; d) activating the first actuating member to rotate the adjustment member and cause the lever to move toward the base plate of the calibration device, thereby applying tension force to the connecting member and structure; 25 e) stopping rotating of the adjustment member when the load cell display shows that a certain load is being applied; f) comparing the load recorded by the load cell as being applied to the structure with the load recorded by the weighing device and, if necessary, calibrating the weighing device to reflect the load recorded by the load cell. 30 Preferably, the calibration device is attached to the mounting surface by sliding the base of the device within the receiving cavity of the anchor member of the invention. Preferably, the method comprises the further step of: 35 g) removing the calibration device from the anchor member and placing the infill of the invention within the receiving cavity of the anchor member of the invention. 4 In yet another aspect, the invention provides a calibration device comprising: a base; first and second levers each having a first end and a second end, the first end of each lever being moveably engaged with the base, and the second end of each 5 lever being pivotably attached to opposing ends of a support member; an adjustment member in the form of a shaft; an actuation member that is engaged with the adjustment member for rotating the adjustment member; a load cell in communication with the support member; and 10 a connector for attaching the calibration device to a load connecting member; wherein at least a portion of the adjustment member shaft is threaded and wherein the first and second levers each comprise a pivotable coupling provided between the first and second ends for engagement with the adjustment member shaft, the coupling of the first lever comprising an aperture having a threaded interior 15 for engagement with the threaded portion of the adjustment member such that rotation of the adjustment member causes the first lever to move along the adjustment member shaft, thereby causing the first and second levers to splay. The term "comprising" as used in this specification and claims means "consisting at 20 least in part of". When interpreting each statement and claim in the specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. 25 The invention consists in the foregoing and also envisages constructions of which the following gives examples only. Brief Description of the Drawings 30 Preferred forms of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a side view of one form of calibration device of the invention; 35 Figure 2 is a plan view of the calibration device of Figure 1; Figure 3 is a schematic representation of the calibration device of Figure 1 in use; 5 Figure 4 is a side view of another form of calibration device of the invention; Figure 5 is a plan view of the calibration device of Figure 4; 5 Figure 6 is a schematic representation of the calibration device of Figure 4 in use; Figure 7 is a side view of the calibration device of Figure 4 in an operating position; 10 Figure 8 is a perspective view of an anchor member according to the invention; Figure 9 is a perspective view of the anchor member of Figure 7 that is fixed to a mounting surface and that is fitted with an infill; and 15 Figure 10 is an end view of the anchor member and infill shown in Figure 9. Detailed Description of Preferred Forms The calibration device of the invention is designed to be able to attach to a structure, 20 such as a hopper, tank, or other receptacle for containing or supporting material to be weighed. A weighing device to be calibrated is in operative communication with the structure so as to be able to weigh the material held within or on the structure. Typically, as material is held within or on the structure, the structure moves downward slightly due to the weight of the material. A strain gauge or other 25 measurement device in communication with the structure measures this movement and converts the distance that the structure has moved into a weight measurement that should reflect the weight of the material within or on the structure. The calibration device of the invention allows a weighing device to be calibrated 30 without needing to apply test weights to the structure or load material into or onto the structure. The device of the invention achieves this by simulating weight applied to a structure by pulling down on the structure. So, for example, it is possible to set up the calibration device of the invention to pull down on a structure to simulate a weight of 1 tonne. The measurement device to be calibrated should, therefore, present a 35 weight of 1 tonne. If it does not, then the device must be calibrated to measure 1 tonne. 6 A preferred form of calibration device is shown in Figures 1 to 3. The device 1 comprises a base 2, a lever 3, and a load adjustment member 4. Preferably, the base 2 is a planar elongate base made of steel plate. 5 The lever 3 comprises a pair of elongate support arms 3a, 3b that are positioned adjacent each other in a spaced apart relationship. Preferably, the support arms are parallel to each other. The lever comprises a first end and an opposing second end. A fulcrum is provided at one end of the base plate 2 and is pivotably attached to the 10 first end of the lever 3 so that the lever can pivot about the fulcrum 6. In particular, each elongate support arm 3a, 3b of the lever is attached to a respective side of the fulcrum in a pivotal arrangement, preferably by a bolt or pin passing through the fulcrum 6 and the support arms 3a, 3b. 15 A coupling, comprising a pin or block having a receiving aperture with a threaded interior, is located between the support arms 3a, 3b and is pivotably attached to each support arm at or near the second end of the lever 3. The load adjustment member 4 comprises a shaft, a portion of which is threaded and 20 fits within the receiving aperture of the coupling so that the threaded portions of the adjustment member and receiving aperture engage with each other. Thus, the load adjustment member 4 is attached to the lever 3 via engagement with the receiving aperture of the coupling. 25 A bracket 7 is attached to the base plate 2 at or near the end of the base plate opposite to the fulcrum 6. A first end of the load adjustment member 4 is attached to the bracket 7 via a pivot shaft, such as a bolt or pin for example. In this form, the load adjustment member 4 is able to pivot about the pivot shaft to vary the angle of the load adjustment member 4 relative to the base plate. However, it is envisaged 30 that other arrangements for pivotably attaching the adjustment member to the base 2 could alternatively be used. In a preferred form, as shown in Figures 1 and 2, the pivot shaft comprises a bearing block 12 having an aperture for receiving the first end of the load adjustment member 35 4. A first actuation member in the form of a motor 8 is connected to the load adjustment member and is able to rotate the adjustment member around its longitudinal axis to turn the shaft of the adjustment member 4 in a clockwise direction 7 and in an anti-clockwise direction. The motor may optionally comprise gears and/or a control system to form a motorised control system for controlling the amount and speed of load applied to a structure. 5 The second, distal end of the adjustment member 4 terminates in a second actuation member in the form of a handle 5 for manually turning the adjustment member in a clockwise or anti-clockwise direction. Needless to say, the device allows the adjustment member to be turned either manually by turning the handle 5, or automatically by operating the motor 8. In an alternative form of calibration device, 10 the device may be configured to provide only a handle so that the device can only be manually operated. Alternatively, the device may be configured to provide only a motorised control system for automatic control of the device. A calibrated load cell 13 is attached to a support member mounted on the lever 3. A 15 digital display 9 is connected to the load cell for displaying the load applied to the structure. Also attached to the lever, via the support member, is at least one connector or link 10 for attaching to a load connecting member, such as a chain or rod or the like. 20 Other forms of the device may comprise a lever formed substantially of a single part rather than a pair of spaced apart support arms. In this form, the lever may comprise a body formed from a solid bar or a hollow tube or box-section, for example. Where the lever is formed as a single part, a first aperture is preferably provided within the lever body, at or near the first end of the lever and through which the pivot shaft for 25 the fulcrum can project. Alternatively, a channel may be formed in the first end of the lever to allow the pivot shaft to be located therein. A second threaded aperture is preferably provided at or near the second end of the lever for engagement with the threaded portion of the load adjustment member. 30 Similarly, although the calibration device has been described as having a threaded adjustment member for engaging with the lever, it is envisaged that the adjustment member may comprise alternative features for engaging with the lever to achieve the same result, as would be readily apparent to a person skilled in the art. 35 In use, the calibration device of the invention may be attached to a mounting surface, such as the ground, below the structure to which the load will be applied. The device may be attached to the mounting surface by any suitable means so that the device is 8 anchored in position. However, it is preferred that the device forms part of a calibration system that includes a detachable anchor member that may be permanently attached to the mounting surface beneath the structure. In this form, the base plate of the calibration device and the anchor member are adapted so that 5 the two components can be attached and detached from each other. An anchor member allows the calibration device to pull down on a load to create tension between the device and the load, or to push against a load to create a compression force between the device and load. 10 The preferred form of anchor member 200 is shown in Figures 8 to 10. The anchor member comprises a rectangular base 201 in the form of a plate having a pair of opposing and spaced apart anchor rails 203a, 203b extending along the length of each long side of the base. Each anchor rail 203a, 203b is also spaced apart from 15 the base by a spacer 202a, 202b. Preferably, each spacer 203a, 203b comprises of an elongate body having side walls that extend along the length of the base of the anchor plate. However, it is envisaged that a plurality of shorter spacers could be utilised instead. Preferably, the anchor rails are substantially parallel to each other. 20 According to the preferred embodiment, the spacers 202a, 202b are integrally formed with the anchor rails 203a, 203b, respectively. The spacers can thus be profile cut or machined from the anchor rails, and the integral anchor rail/spacer secured to the base 201 by way of fastening means such as anchor bolts 207. Alternatively, or additionally, the spacers 202a, 202b may be integral with the base 201, or formed 25 separately from both the anchor rails and the base plate without departing from the scope of the invention. Although the preferred form of anchor member comprises a rectangular base with parallel spacers and anchor rails, it is envisaged that the base could be any suitable 30 shape for engaging with the base of the calibration device of the invention that may also be of any suitable corresponding shape. Alternatively, the anchor rails above may be shaped to correspond to the shape of the base of the calibration device. For example, one end of the spacers and anchor rails may be positioned proximate to each other while the other end of the spacers and anchor rails are positioned further 35 apart from each other to define a receiving cavity having a shape that corresponds with a calibration device having a base that is of a triangular or trapezoidal shape. 9 The spacers and anchor rails are arranged so that the distance between the inner side walls 204a, 204b of each spacer 203a, and 203b is greater than the distance between the anchor rails 203a, 203b. Thus, the spacers and anchor rails are arranged so that a portion of each rail projects beyond the respective spacer toward 5 the opposing anchor rail to form overhanging flanges along the length of the anchor plate. The base of the anchor plate 201, inner side walls of the spacers 204a, 204b, and overhanging anchor rails 203a, 203b define an open-top receiving cavity 205 within 10 which at least a portion of the base of the calibration device can be received, as will be discussed below. A protective infill 300 can also be slid into this cavity when the anchor plate is not being used to anchor a calibration device, as shown in Figures 9 and 10. Preferably, the protective infill 300 is shaped to slide easily within the receiving cavity. 15 The protective infill 300 may comprise a base and an upper portion 301 projecting from the base, which may be profile cut or machined, for example. The upper portion is profiled to fit between the projecting anchor rails 203a, 203b and to have an upper surface 302 substantially the same height as the upper surface 206a, 206b of each 20 anchor rail so that the upper surface of the anchor plate is substantially flush when the infill is housed within the plate. In the preferred form, both the base and the upper portion are substantially rectangular. In this form, the width of the upper portion is less than the width of the base and is substantially the same as the distance between the projecting anchor rails. The width of the base is substantially 25 the same as the distance between the spacers in order to allow the infill to fit snugly within the receiving aperture. The infill prevents ingress of debris into the receiving cavity of the anchor plate and also prevents damage to the anchor rails. The anchor member is preferably made of stainless steel to resist corrosion and to 30 withstand harsh environmental conditions. Its low profile means that it can remain permanently positioned onsite without presenting an obstruction to activity onsite and with minimal risk of being damaged itself. Prior to use, the anchor member is affixed to a mounting surface, such as by using 35 stainless steel threaded rods that are driven through preformed apertures in the anchor plate and into the mounting surface to which the plate is being affixed. The mounting surface could take many forms, such as a concrete pad, tar seal, or a 10 platform. Chemical cements, concrete cement, and or nuts and washers may also be used to permanently attach the plate to a mounting surface. Other suitable forms of attaching the anchor member to a mounting surface may alternatively be used, as would be readily apparent to a person skilled in the art. 5 The operation of the calibration device and system of the invention will now be described by referring to the use of the calibration device to apply a load to a hopper, as shown in Figure 3. However, it will be appreciated that the calibration device and system may be used to apply a load to any suitable receptacle or other structure. 10 The base plate 101 of the calibration device 100 is first slid into the receiving cavity 205 of the anchor member 200 so that a portion of the base plate upper surface lies directly below the projecting lower surfaces 208a, 208b of the anchor rails 203a, 203b of the anchor member. 15 An adaptor plate 16 is attached to the connector or link 10 of the calibration device 100. One end of a connecting member, such as a chain or rod 15 or the like, is attached to connectors or links 14 positioned on opposing sides of the hopper and the other end is attached to a connecting point provided on the adaptor plate 16 so 20 that the chains or rods are under tension. The adapter plate 16 allows one or more connecting members to be brought to a common centre point so that a tension force applied by the calibration device 100 is applied to the correct single point on the load cell to ensure an accurate reading. The adapter plate may also be provided with multiple connecting points arranged in a vertical pattern so that the effective length of 25 the connecting members may be adjusted without altering the connecting members themselves, by selecting the appropriate connecting points. The load adjustment member 4 is then rotated about its longitudinal axis either manually by rotating the handle 5, or automatically by the motorised control system 30 8. As the load adjustment member 4 is rotated in one direction, its threaded shaft, which is engaged with the threaded receiving aperture of the lever 3, causes the second end of the lever 3 to move down along the length of the load adjustment member 35 toward the base plate 2 while the first end of the lever pivots about the fulcrum 6. As the lever moves toward the base plate, the chain or rod 15 pulls on the connectors 14 attached to the hopper, thus pulling down on the hopper to apply a tension force that 11 simulates weight within the hopper. As the tension force is applied to the hopper, the calibration device is firmly anchored to the mounting surface because the upper surface of the base plate 2 of the calibration device is prevented from pulling out of the anchor member by the projecting anchor rails 203a, 203b. 5 The load adjustment member 4 and lever 3 provide two mechanisms for creating a mechanical advantage, multiplying the torque applied to the load adjustment member by the operator (via the handle 5) or the motor 8. This means that an operator can apply various different loads to the hopper ranging from approximately 1kg to 10 100,000kg, depending on the capacity of the load cell in the calibration device and the capacity of the hopper, by simply varying the extent to which the load adjustment member is rotated. The calibrated load cell 13 measures the force applied to the hopper by the 15 calibration device 100 and displays the simulated weight applied to the hopper on the digital display 9. The operator compares this display with the measurement taken by the measurement device to be calibrated. If necessary, the measurement device is then calibrated to show the correct load. 20 This form of calibration device allows a person to apply a load of at least 2000kg by hand to the weighing system under test. By the use of a small lever on the handle 5 or load adjustment member 4, 5000kg can easily be applied. The load adjustment member 4 is therefore preferably provided with means for engaging a lever, such as the hexagonal shaft 5a adapted for engagement with a spanner, to increase the 25 loading. Once the calibration is complete, the load adjustment member 4 is rotated in the opposite direction to slacken the tension on the chains or rods 15 and release the force applied to the hopper. The chains or rods 15 are then disconnected from the 30 hopper 17 and calibration device 1 and the calibration device is removed from the anchor member 200. An infill 300 is slid into the anchor member 200 to protect it while not in use. The calibration device can then be transferred to the next site where calibration is necessary. 35 Although described in the above example as being used to apply a tension force, the calibration device 100 may also be adapted for applying a compressive force to a hopper, receptacle or other structure. In this case, the connecting member would 12 typically be a rigid member such as a rod or a bar to apply the compressive force directly to the hopper. A second form of calibration device 100 is shown in Figures 4 to 7. This form of 5 device comprises an elongate base plate 101 and an upper plate 111 that is spaced apart from and is substantially parallel to the base plate. The upper plate is supported by a pair of side spacers 112 that are positioned at or near each end of the base plate 101 and a central spacer 118 positioned between the side spacers. The base plate 101, upper plate 111, side spacers 112, and central spacer 118 define a 10 first roller cavity 114a, within which at least one first roller 116a is located, and a second roller cavity, within which at least one second roller 116b is located. The first and second roller cavities are separated by the central spacer 118. A pair of first and second levers 103a, 103b are also provided, each lever having a 15 first end and an opposing second end. At least one roller 116 is attached to each of the first and second levers 103a, 103b at a first end of the lever and each lever is thus moveably engaged with the base by way of the respective rollers abutting the upper plate 111 when housed within the respective roller cavity 114a, 114b. 20 The first and second levers 103a, 103b may each comprise one or more distinct lever arms sharing the same pivotal axes, but are described herein as being a single lever for the purpose of convenience. According to the most preferred embodiment, for example, the first lever 103a comprises a pair of distinct lever arms 119a, 119b provided on opposing sides of the support member 107, and the second lever 103b 25 similarly comprises two lever arms 120a, 120b. This configuration is preferred to balance the tension force applied to the connector or link 110, but alternative configurations are possible without departing from the scope of the invention. For example, the opposed lever arms may be formed from a single piece and therefore comprise a single lever arm, or three or more lever arms may be provided in each of 30 the first and second levers 103a, 103b. Each lever arm 119a, 119b, 120a, 120b is preferably provided with an independent roller, or a single roller may alternatively be provided between each adjacent pair of lever arms. Where reference is made below to the rollers 11 6a, 11 6b attached to the 35 first and second levers 103a, 103b, respectively, the term "roller" is to be taken as meaning the set of rollers provided at the first end of the respective lever, whether such set comprises one or more rollers. 13 A support member 107 is attached to the levers 103a, 103b at or near the second ends of the levers via pivots 113a, 113b so that the levers are able to pivot relative the support member 107. 5 A calibrated load cell 115 is mounted on the support member 107 and is attached to a display screen 109. At least one connector or link 110 is also supported by the support member and is in communication with the calibrated load cell 115. 10 An elongate load adjustment member 104, having a first end portion, which is entirely or at least partly threaded, and an opposing second end portion, is attached to each of the levers 103a, 103b at a location on the levers below the mid-point between the upper plate 111 and the support member 107. In particular, the threaded portion of the first end of the load adjustment member is attached to the first lever 103a via a 15 first pivot shaft or block 105 that comprises a receiving aperture having a threaded interior. The threaded portion of the adjustment member engages with the threaded interior of the receiving aperture to pivotably attach the adjustment member to the first pivot shaft or block 105 such that the first lever 103a can pivot relative to the load adjustment member 104. 20 The second end portion of the load adjustment member 104 is attached to the second lever 103b via a second pivot shaft or block 106 having a receiving aperture that is adapted to receive the second end portion of the load adjustment member 104 in such a way that the second end portion can rotate within the aperture. Thus, it is 25 not essential for the second end portion of the load adjustment member, or the interior of the receiving aperture of the second pivot shaft or block, to be threaded. A motor 108 is attached to the load adjustment member and is adapted to rotate the adjustment member 104 about its longitudinal axis. 30 The rollers 116a, 116b, and pivoting joints or connections within the calibration device allow the device to move between a neutral position and an operating position, in which the device applies a force to a structure. 35 In use, the base plate 101 is slid into the receiving cavity 205 of the anchor member 200 that is fixed to a mounting surface below a hopper or other structure to which a load is to be applied in order to simulate weight held by the structure. Alternatively, 14 the base plate may be anchored to the mounting surface by any other suitable means, such as by screwing, bolting, or adhering the base plate to the mounting surface for example. 5 The device is placed in the neutral position, shown in Figure 4, in which the first ends of the first and second levers 103a, 103b are in a position proximate to the central spacer 118 and the length of the adjustment member 104 located between the first and second lever arms is substantially equivalent to the length of the support member 107. An adaptor plate 16 is then attached to the connector or link 110. One 10 end of one or more chains or rods 15 or the like is attached to connectors or links 14 positioned on the hopper and the other end of the one or more chains or rods is attached to the adaptor plate 16 so that the chain(s) or rod(s) is/are under tension. Once the device has been attached to the structure in this way, it is possible for the device to move from the neutral position to the operating position, shown in Figure 7, 15 in which the device applies downward force on the structure to simulate weight. To cause the device to adopt the operating position, the motor 108 rotates the load adjustment member 4 in one direction about its longitudinal axis. The engagement of the rotating threaded portion of the load adjustment member 104 with the threaded 20 interior surface of the receiving aperture of the first pivot shaft 11 3a causes the pivot shaft and, consequently, the first lever 103a attached to the first pivot shaft, to move toward the first end of the adjustment member 104. The roller 116a attached to the first end of the first lever 103a consequently moves in the same direction within the first roller cavity 114a until it abuts the inner wall 117 of the respective side spacer 25 112. Meanwhile, the first end of the second lever is forced in the opposing direction towards the inner wall 117 of the corresponding side spacer 112, due to the interaction of the forces between the upper plate 111, device 100 and the structure e.g. hopper 17. The device 100 according to this preferred embodiment is thus self centering about the central spacer 118. Consequently, the second lever 103b is 30 caused to pivot about its first end so as to slope toward the first lever. Similarly, the first lever 103a is caused to pivot about its first end to slope toward the second lever as the length of the load adjustment member 104 between the levers 103a, 103b exceeds the length of the support member 107. Thus, in the operating position, the first and second levers 103a and 103b splay apart and the device adopts a 35 trapezoidal shape defined by the load adjustment member 104, levers 103a, 103b, and support member 107, as shown in Figure 7. 15 Because the levers 103a, 103b are sloped toward each other in the operating position, the support member 107 moves downward toward the base plate 101. This, in turn, applies tension to the chains or rods 15 causing the chains or rods to pull down on the hopper to simulate weight. 5 Those skilled in the art will appreciate that the force applied by this embodiment of the invention is non-linear with respect to the rotation of the adjustment member. From the neutral position, splaying of the first and second levers 103a, 103b upon actuation of the adjustment member 104 initially causes relatively minimal downward 10 movement of the support member 107. However, as the first lever 103a approaches the first end of the adjustment member 104, a greater degree of vertical movement of the support member 107 is obtained for each rotation of the adjustment member. This non-linearity allows a substantial force to be applied to the hopper or load relatively rapidly. 15 The extent of force applied to the hopper depends on the extent to which the first lever 103a has been caused to move along the adjustment member 104. The point at which the maximum amount of force can be applied to the hopper is the point at which the roller 11 6a of the first lever abuts the side wall 117 of the side spacer 112 20 adjacent to the first roller cavity 114a. To remove the force, the motor is again operated to rotate the adjustment member in the opposite direction, causing the calibration device to return to the neutral position. Although this form of calibration device has been described as having a roller 25 attached to the first end of the first lever and a roller attached to the first end of the second lever, it is envisaged that the first end of the second lever could, alternatively, be located at a fixed point about which the second lever can pivot. In other embodiments, the first end of the lever or levers may be moveably engaged with the base by way of a carriage arrangement, or other such variations allowing for 30 movement in two opposing horizontal directions, without departing from the scope of the invention. In another form, the single threaded shaft of the load adjustment member may be replaced with a turnbuckle. In this form, the receiving aperture in the second pivot 35 shaft, which is attached to the second lever, is threaded so that by rotating the turnbuckle, the first ends of both the first and second levers are caused to move 16 away from each other. Consequently, the support member is caused to move downwardly toward the base of the device to apply load to a structure. Thus, the invention provides a portable calibration device that can be used to apply a 5 tension force or compression force to a structure. By avoiding the need to load the structure with test weights, the use of the device and calibration system is easier and safer. Furthermore, the calibration device and system of the invention provide a high degree of accuracy that is repeatable with each use. 10 The invention also relates to a kit of parts comprising a calibration device according to the invention, together with an anchor member according to the invention and, optionally, at least one connecting member for connecting the device to a structure, and an infill for insertion into the anchor member. 15 The above describes preferred embodiments of the invention only. Modifications that readily appear to those skilled in the art can be made to the invention without departing from the scope of the invention. 17

Claims (21)

1. A calibration device for calibrating weight measurement apparatuses, the device comprising: 5 a base having a first end and a second end; a lever having a first end and a second end, the first end of the lever being pivotably attached to the base at or near the first end of the base; an adjustment member in the form of a shaft having a first end and a second end, the first end of the adjustment member being pivotably attached to the 10 base at or near the second end of the base; a first actuation member that is engaged with the adjustment member for rotating the adjustment member; a load cell in communication with the lever so as to sense vertical movement of the lever, the load cell being connected to a digital display for 15 displaying a load calculated by the load cell; and a connector for attaching the calibration device to a load connecting member; wherein at least a portion of the adjustment member shaft is threaded and wherein the lever comprises a coupling at or near the second end of the lever, the 20 coupling comprising an aperture having a threaded interior for engagement with the threaded portion of the adjustment member such that rotation of the adjustment member causes the lever to move along the adjustment member shaft.

2. The calibration device of claim 1 wherein the lever comprises a pair of support 25 arms positioned adjacent to each other in a spaced apart relationship and wherein the coupling is located between the support arms and is pivotably attached to each support arm.

3. The calibration device of claim 1 or 2, wherein the first actuation member 30 comprises a handle attached to the second end of the adjustment member.

4. The calibration device of claim 1 or 2, wherein the first actuation member comprises a motor. 35

5. The calibration device of claim 3 and further comprising a second actuation member comprising a motor. 18

6. The calibration device of any one of the preceding claims, wherein the base of the device is substantially planar.

7. An anchor member adapted to be used with the calibration device of any one of 5 the preceding claims, the anchor member comprising a base adapted to be attached to a mounting surface, the base comprising a pair of anchor rails substantially spaced apart from each other, each anchor rail also being spaced apart from the base of the anchor member by at least one spacer; wherein the spacers and anchor rails are arranged so that a portion of each anchor rail projects beyond the respective spacer 10 toward the opposing anchor rail to form an overhanging flange, wherein the base of the anchor member, the spacers and the projecting anchor rails define a receiving cavity adapted to receive at least a portion of the base of the calibration device therein. 15

8. An anchor member as claimed in claim 7, wherein each spacer is substantially parallel to the opposing spacer and each anchor rail is substantially parallel to the other.

9. An infill for insertion into the receiving cavity of the anchor member of claim 7, 20 the infill comprising a base and an upper portion projecting from the base, the base and upper portion being profiled to fit snugly within the receiving cavity of the anchor member.

10. A kit of parts comprising a calibration device according to any one of claims 1 to 25 6 and further comprising an anchor member, wherein the anchor member comprises a base adapted to be attached to a mounting surface, the base comprising a pair of anchor rails substantially spaced apart from each other, each anchor rail also being spaced apart from the base of the anchor member by at least one spacer; wherein a portion of each anchor rail projects beyond the respective spacer toward the 30 opposing anchor rail to form an overhanging flange, wherein the base of the anchor member, the spacers and the projecting anchor rails define a receiving cavity adapted to receive at least a portion of the base of the calibration device therein.

11. The kit of parts of claim 10, wherein the opposing spacers and anchor rails are 35 substantially parallel to each other and wherein the base of the calibration device comprises two opposing substantially parallel sides profiled to fit within the receiving cavity of the anchor member. 19

12. The kit of parts of claim 10 or 11 and further comprising at least one load connecting member for connecting the calibration device to a structure to which a load is to be applied 5

13. The kit of parts of claim 12, wherein the load connecting member comprises a chain or rod.

14. The kit of parts of any one of claims 10 to 13, further comprising an infill comprising a base and an upper portion projecting from the base, wherein the base 10 of the infill is profiled to fit between the spacers of the anchor member and the upper portion of the infill is profiled to fit between the projecting anchor rails of the anchor member.

15. A method for calibrating a weighing device for weighing load applied to a 15 structure, the method comprising the steps of: a) providing a calibration device according to claim 1; b) attaching the calibration device to a mounting surface below the structure; c) attaching at least one connecting member to the calibration device and to 20 the structure so that the connecting member is under tension; d) activating the first actuating member to rotate the adjustment member and cause the lever to move toward the base plate of the calibration device, thereby applying tension force to the connecting member and structure; e) stopping rotating of the adjustment member when the load cell display 25 shows that a certain load is being applied; f) comparing the load recorded by the load cell as being applied to the structure with the load recorded by the weighing device and, if necessary, calibrating the weighing device to reflect the load recorded by the load cell. 30

16. The method of claim 15, wherein the calibration device is attached to the mounting surface by sliding the base of the device within the receiving cavity of the anchor member of claim 7.

17. The method of claim 16 further comprising the step of: 35 g) removing the calibration device from the anchor member and placing the infill of claim 9 within the receiving cavity of the anchor member. 20

18. A calibration device comprising: a base; first and second levers each having a first end and a second end, the first end of each lever being moveably engaged with the base, and the second end of each 5 lever being pivotably attached to opposing ends of a support member; an adjustment member in the form of a shaft; an actuation member that is engaged with the adjustment member for rotating the adjustment member; a load cell in communication with the support member; and 10 a connector for attaching the calibration device to a load connecting member; wherein at least a portion of the adjustment member shaft is threaded and wherein the first and second levers each comprise a pivotable coupling provided between the first and second ends for engagement with the adjustment member shaft, the coupling of the first lever comprising an aperture having a threaded interior 15 for engagement with the threaded portion of the adjustment member such that rotation of the adjustment member causes the first lever to move along the adjustment member shaft, thereby causing the first and second levers to splay.

19. A calibration device substantially as herein described with reference to the 20 accompanying drawings.

20. The kit of parts of claim 10 and substantially as herein described with reference to the accompanying drawings. 25

21. The method of claim 15 and substantially as herein described with reference to the accompanying drawings. 21