TENSION FORCE METER

Abstract: Device for measuring tension force in web alt. wire without giving any permanent affect on the measured object (7). In goods transportation it is common to use webs to tie down (lash) the load to the load carrier. Then it is important that right pretension force is applied to achieve a safe transport. The aim is to be able to check this force before but even during the transport. This wish is solved with a hand carried device that can be moved across the measured object (7) from the side, perform the measurement after activation arm has been pulled and be removed after deactivation without having any remaining affect on the lashing. Technically this is done when the activation forces the object (7) to bend over a number of rolls (17, 18). This bending calls for a force perpendicularly to the web/wire (7) that is registered, recalculated (calibrated) and displayed as the searched force in the object. To achieve high accuracy the instrument is equipped with two widthsetters which correct set allows exact positioning sidewise of the measured object and a device that can be adjusted and compensates the force for the free length of the object (7). Besides the instrument has an automatic power control which alarms when the battery must be changed.

Description: PCT-application Priority SE 9600636-6, dated 1996-02-20. Tension Force Meter Following invention describes a device to measure tension force in pretensioned web alt. pretensioned wire without having any remaining affect on the measured object ( The lashing ). The device that is primarily expected to find its use in the transport sector is a portable easy handled control instrument for authorities, transporters and senders. Background of the invention Background of the invention is the need in the transport sector for the possibility to easily and quickly check tension force in lashing bands to secure wished pretension forces in order to increase traffic safty and decrease transport damages. Technical problem The ability to control the so called pretension force in webs ( alt. wires ) is of outermost importance in transport to achieve safe securing of cargo to carrier. This control should also be possible to be carried out in such a way that it doesn ' t permanently affect the lashing. Today there are no such equipment that meet the above demand. State of developement Measuring tension force in wire or similar objects by bending it over three points and meausure the force across the object for actual bending (approx. a linear function of the tension force), recalculate it to tension force (alt. calibrate it against actual force) and present it as the wanted force is since long known technique. This was described already 1929 in the patent US 1,722,036 and later in among others US 1,871,776, US 3,653,258, US 3,698,244 US 4,860,597 and now latest in US 4,860,597 and FR 2 71 1 425. The technique, that mostly has been used for wires, has had its main use for lifting devices ( cranes, traverses etc.) where it has been used as so called overload protection. Because of that, the existing equipment is designed for wire and mainly planned to be used in fixed installations. The technique is not used in the transport sector, as well as on the type of lashing bands that are so common. For that reason no portable easy handled instrument has been developed for meausering tension force in webs alt. wires. Purpose of the invention and its most significant identification The purpose of the invention is to supply a device that makes it easy to check the force momentarily in a lashing from the time it is tightend until it is untightened. Consequently the tension force meter ways only approx. 3 kg and has the dimension approx. 20 10x30 cm. To achieve bending of the measured object the device hosts rolls / axles. Beside that there is a measure unit ( mechanical or electronic ) that registrates the needed force to produce actual bending and by recalculation / calibration displays the searched tension force. A significant advantage with a device according to the invention is that it easily can be moved across the object, perform the measuring and as easily be removed without having any remaining affect on the lashing. This calls of course for geometries chosen so that the measured object permanently is in its elastic state. Description of the invention With support of fig. 1-4 in view from right above a device called tension force meter according to the invention will be described Figure 1 shows a chosen design for the desribed device together with a peace of the measured object ( in this case a web ). Figure 2 shows the chassis. Figure 3 shows the most important parts of the mechanical measuring device. Figure 4 shows measure electronics. Figure 1 shows a preferable chosen technical solution that corresponds to the invention. It shows among other things the chassis 1 that work both as "holder" of important geometric points for the device as well as force collector and protector shell for the more important parts in the invention. To the chassis (1) is screwed the front gable 2 resp. rear gable 3 which completes the instrument case. The gables (2,3) have longitudanal grooves that give room for the measured object. Pos.4 shows the handle by witch the instrument is manouvered. No.5 is the activating lever that when pulled to a vertical position rotates in the measure unit 6 (fig. 3) towards the measured object 7 and bends it. The guiding list 8 simplifices the introdution of the measured object into the instrument. The knobs for front and rear widthsetters is shown by 9 and 9 ". Also the knob for the lengthsetter 10 and the both battery boxes 11 ' and 11 " can be seen. Figure 2 shows the chassis (1) with it's four sides 12 (upper side), 13 (handle side), 14 (bottom) and front side 1 . The front side is by a longitudunal opening 16 along its full length devided in an upper part 15' and a lower part 15". Figure 3 shows the mechanical parts inside the chassis and a measured object (7). The measure unit (6), that through a rotational movement bends the measured object (7) between the support rolls 17 and 18, consist of among other things a roll 19 mounted in bearings, a measure wagon 20, a load cell 21 and a carrier axle (22) which is carried in bearings in the chassis (1). 23 and 24 are widthsetters with the stopplates 25,26 that act as stops for the measured object and which correct set centers the object (7) sidewise under the measure unit (6). Figure 4 shows the electronic unit 27 which is protectedly placed inside the chassis. The tension force meter is additionally equipped with a switch (not shown in figure) for power supply. This can be arranged in such a way that it is controlled by the activating lever (5). When the activating lever is in rest position (down) all power is shut off but opens automatically when the lever is pulled. Above is described a technical solution where the measure unit (6) bends the measured object (7) by being rotated into the object. This movement can be replaced by a translation vertical towards the measured object. The technic is useable on all webtypes and wires as long as the geometry is chosen so it is possible to neglect bending stiffness for the measured object. That means the suffer the web /wire is the larger geometries (distances, rollradies etc.) must be chosen. Important for the measure accuracy is also that no friction force is lost in support rolls or measure roll why in these contacts there should only exist normal forces towards axle centers. Because of that these components preferably should be mounted in bearings. Of the same reason the widthsetters are important. Correct set friction forces are minimised in the measure unit at the same time as mislined forces are avoided. Preferably measure geometrie for normal lashing bands with recommended pretension force 5 kN is for example 200 mm between the support rolls and 5-20 mm bending perpendicular to the web. The diameters for the measure roll and the support rolls can at the same time be approx. 20 mm.

Claims: PATENT CLAIMS Device for momentarely measuring of tension force in web alt. wire consisting of a chassis (1) which allows the measured object (7) to freely be moved into the device, which also hosts among other things a measure unit (6) and support rolls (17,18). recognised by the chassis consists of four longitudunal sides (12,13,14,15) of which one side (15) is cut off along its full length by a opening (16) which divides the side in a upper part (15 ) and a lower part (15"). Device according to claim 1 recognised by the lower part of the cut off side (15") is support (or bearing holder) for one end of the support rolls. Device according to claim 1,2 recognised by the upper part of the cut offside (15 ) holds and hosts among other things a measure unit (6) and widthsetters (23,24). Device according to claim 1-3 recognised by the measure unit (6) among other things has a roll (19) mounted in bearings in a measure wagon (20), a device for force measuring (21 ) and a carrier axle (22). Device according to claim 1-4 recognised by the device has front and rear widthsetters (23,24) carrying sidewise adjustable stopplates (25,26) which correct set centers the measured object (7) under the measure unit (6). To help this setting the gables are equipped with a special centering measurescale 28. Device according to claim 1-5 recognised by the device is equipped with a knob (10) which affect the electronics and allows measure compensation for the object ' s free length. Device according to claim 1-6 recognised by in the cut off side's lower part (15") is a angle profile (8) assembled along its full length which makes it easier to move the measured object into the device. Device according to claim 1-7 recognised by the measuring electronics (27) and batteries (11 ', 1 1 ") are totally covered and protected by the chassis (1 ). Device according to claim 1-8 recognised by when the activating arm is turned to rest position (start position) all power is shut off to automatically be turned on when measuring. Device according to claim 1-9 recognised by the instrument case has a front and rear gable (2,3) with long grooves, which give room for the measured object when it is moved in. The gables make the instrument case stiffer. Device according to claim 1-10 recognised by existing solutions which through measure electronics compensate the measurevalue for different features of the measured object and different temperatures.

Inventors: KENNETH BAECKLUND LARS, KENNETH, BAECKLUND, LARS
Applicants: KENNETH BAECKLUND LARS, KENNETH, BAECKLUND, LARS
Application year: 1997
Main classification: G01L5
IPC codes: G01L5