JPS622248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for measuring large loads that measure large loads applied to relatively flexible members such as structures made of steel plates, stiffeners, etc. (hereinafter simply referred to as steel structures). Regarding equipment.

For example, a deck lift type offshore oil drilling rig called a jack-up type rig is a platform that has several legs that can be raised and lowered and is equipped with various oil drilling equipment. The platform is towed while floating due to the buoyancy of the platform, and during work, the legs are lowered to the seabed, and the platform is then jacked up to a sufficient height above the sea surface, creating a stable working environment unaffected by waves and currents. It is often used as the most advantageous drilling equipment in terms of workability, safety, economy, etc., and is capable of conducting test drilling in offshore oil fields. When working on this jack-up platform, when the legs are lowered to the seabed and the platform is jacked up to a sufficient height above the sea surface, the rig must be monitored to ensure it does not capsize and the rig must be stably installed. Therefore, it is mandatory to install a measuring device to measure the load on each leg. As a result, there has been a demand for load measuring devices for oil rigs, maintenance barges, and other jack-up platforms used particularly in the North Sea.

As a load measuring device for the above-mentioned jack-up type rigs, etc., a hydraulic load cell has traditionally been used, in which a bag-shaped pad filled with oil is inserted into the load transmission path, and the load is determined from the hydraulic pressure inside the pad. .

However, in the case of this hydraulic load cell, measurement errors due to changes in oil temperature appear significantly, making it extremely difficult to compensate for the temperature, and there is also a risk of damage due to stress concentration at the edges when a large load is applied. However, it also had drawbacks such as difficulty in its manufacturing method.

In view of the shortcomings of the conventional devices, the inventors of the present invention attempted to use a strain gauge type load transducer in place of the hydraulic load cell, and encountered the following problems.

That is, for example, a jack-up type rig is a so-called steel structure, and in particular, the support part (top plate) of the jack-up house that supports the reaction force received from the legs is also a steel structure and is made of a relatively flexible member (steel plate). , uniform load is not transmitted to the load converter, making accurate load measurement impossible. To deal with this problem, measurement accuracy can be improved by inserting a pad made of thick plate material with high rigidity between the load transducer and the part to be measured of the structure, but the thickness of the pad The jack house has to be correspondingly taller, creating additional problems resulting in an increase in the weight and material costs of the entire structure. These problems will be explained in more detail with reference to the drawings.
FIG. 1 is a front view showing an example in which a strain gauge type load transducer is incorporated into a rolling mill. This rolling mill feeds a plate from the direction A in the figure between upper and lower rolling rollers 1 and 2, and rolls the plate to a predetermined thickness adjusted by an adjustment screw 3 provided above. The loads applied to parts 4, 5, 6, 7, and 8 are transferred to a washer type load converter 9 and a flat type load converter 1.
It is arranged to measure at 0.11. In this rolling mill, each of the support parts 4, 5, 6, which abuts the main body part 12 and each load converter 9, 10, 11,
7 and 8 have increased rigidity, so the deformation of each support part is almost negligible, and if you pay attention to the parallelism of each support part and the load converter, the load on each support part can be reduced. It is possible to accurately measure the load applied.

However, in steel structures as shown in the plan and front views in FIGS. 2 and 3,
The upper support plate (top plate) 14 and the lower support plate 15 that are in contact with the cylindrical load converter 13 are both made of flexible and easily deformable steel structures. One of the two is movable toward and away from the other in the vertical direction, and is provided with a shock pad 16 for absorbing impact upon contact and a pad 17 for preventing partial deformation of the shock pad 16.

When a load is applied to such a steel structure from below, for example, the pad 17 and the upper support plate 1
An inclined load or unevenly distributed load is likely to be applied to the fourth
As shown in the figure, the upper support plate 14 and the pad 1
7 etc. are deformed, and the contact surface to the load converter 13 is also deformed into a wave shape. For example, when the upper support plate 14 (indicated by the two-dot chain line) is curved upward as shown in FIG. It decreases as it approaches . On the other hand, if the upper support plate 14 is curved downward, the stress distribution will be as shown in FIG. When an unevenly distributed load is applied to the pressure receiving surface of the load converter 13 in this way, the relationship between the load and the measured value loses linearity, and for example, in the case of Fig. 5, the measured value is smaller than the actual load, and in the case of Fig. 6 In both cases, accurate measurements cannot be taken. In order to eliminate this drawback, as shown in _FIG . or by inserting a plate 19 with a large plate thickness h ₃ and high rigidity and increasing the height h ₄ of the load transducer 13 as shown in FIG. 8a. It has been found that the stress distribution becomes as shown in FIGS. 7b and 8b, the load is equalized on the pressure receiving surface of the load converter 13, and the reproducibility of the load, that is, the measurement accuracy can be improved.

However, as shown in FIG. _7a and FIG.
h ₃ , the height h ₄ of the load converter 13, etc. become large, so the height H between the upper support plate 14 and the lower support plate 15 also becomes large, resulting in an increase in weight and cost. Not only that, but the problem remains that it becomes weak against lateral loads.

The present invention has been made to solve these problems, and is capable of measuring large loads applied to comparatively flexible members such as steel structures with high accuracy, and is capable of measuring small weight, low cost steel structures, etc. The purpose is to provide a large load measuring device.

An embodiment of the present invention is shown below in FIGS. 9 and 10.
This will be explained based on FIG.

In FIGS. 9 to 11, 20 is the internal space 2
1, the load transducer has a cylindrical overall shape, is arranged vertically, and has an annular protrusion 23 integrally formed on the upper end surface 22 side, and has a cylindrical inner peripheral surface and an outer peripheral surface. A plurality of strain gauges 24 are attached at appropriate positions on the surface to convert the load into an electrical quantity. Reference numeral 25 denotes a disk-shaped upper abutting plate, which
It is abutted (placed) on top. Reference numeral 26 denotes a cylindrical projection sheet, which is provided at the center of the upper surface of the upper backing plate 25. This protrusion sheet 26 may be placed on the upper backing plate 25 or may be integrated. That is, the lower end may be fitted to this upper backing plate 25, or furthermore, the upper backing plate 2
It may be formed integrally with 5. Here, the projection sheet 26
It is preferable that the diameter d is as small as possible within the range that the supporting member (the upper common sheet 39, which will be described later) that comes into contact with the upper surface of the projection sheet 26 can withstand in terms of material strength. Further, the thickness t of the protrusion sheet 26 only needs to be slightly thicker than h ₁ h _3. Incidentally, in the above embodiment, the thickness t of the protrusion sheet 26 is at most 10
It is formed to be less than mm.

Large load measuring device 27 configured as described above
is used with the load converter 20 installed on the base and the protruding sheet 26 supporting the load object. As shown in FIG. 12a, the projection sheet 26
When the loaded object that comes into contact with the upper surface is a relatively flexible member 28 such as a steel structure, the entire member 28 is deformed in a wavy manner, and the stress distribution of the member 28 is also wavy in accordance with the deformation. will be presented. and,
The protruding sheet 2 contacts the member 28 and receives the load.
6 receives an unevenly distributed load, so that the stress distribution on its surface is small at the center and becomes larger toward the periphery, as shown in FIG. 12b, for example. However, the unevenly distributed load received by the protruding sheet 26 is concentrated at the protruding sheet 26, and the pressure receiving area of the protruding sheet 26 is becoming smaller, so that the uneven distribution load that occurs on the loaded object, that is, the member 28, is reduced. It functions to prevent bending moments caused by distributed loads from being transmitted to the upper backing plate 25 and load converter 20. Furthermore, when the load is transmitted to the load converter 20 via the upper backing plate 25, the upper backing plate 2
5, the stress is diffused (dispersed) within the load transducer 20
At the stage reaching the protrusion 23 provided on the upper end surface 22 side, the stress distribution is considerably homogenized as shown in FIG. 12c. Further, at the stage of reaching the upper end surface 22 of the load converter 20 via the protrusion 23, the stress smoothing function of the protrusion 23 causes the upper end surface 22 to
The load applied to the surface becomes a uniformly distributed load, and the stress distribution becomes uniform over the entire pressure-receiving surface as shown in FIG. 12d. This means that the integrated value of the stress on the upper end surface 22 of the load transducer 20 exactly matches the integrated value of the stress on the member to be measured 28 shown in FIG. 12a. Therefore, the load is correctly transmitted to the strain gauges 24, 24, .
24... can be taken out. Further, according to the above-mentioned configuration, the thickness (height) of the protruding sheet 26 and the upper backing plate 25 may be small, and the height of the load converter 20 may be low enough to perform load measurement with high accuracy. It is very advantageous to reduce weight and cost.

Next, an example in which the large load measuring device 27 of the present invention is applied to the above-mentioned jack up platform will be described with reference to FIGS. 13 to 15. 29 is a leg having a pair of racks 30; 31 is the rack 3;
a support frame body with a pinion 32 that engages with 0; 3;
3 is a pinion drive device. The support frame 31
A shock pad 34 is attached to the upper surface of the holder. On the lower common seat 37 supported by a plurality of hanging bolts 36 from the top plate side of the jack house 35, three large load measuring devices 27 are installed via lower backing plates 38, and each protruding seat 26 ,
It abuts from below against an upper common sheet 39 attached to the lower surface of the jack house 35.

The operation of the large load measuring device for the jack-up platform having such a configuration will be explained.

As mentioned above, when the jack platform is moved, the pinion drive device 33 rotates the pinion 32 in the direction shown, and the rack 30 that engages with the pinion 32 and the leg 29 that is integral with the rack 30 are rotated by the pinion drive device 33.
to rise. Since the platform floats due to its own buoyancy, it is towed in that state to the target offshore oil field location.

Next, when drilling (test drilling) an offshore oil field, the pinion drive device 33 is driven in the opposite direction to the above-mentioned direction.
9 to the seabed, and then jack up the platform to a sufficient height above the sea surface. On this occasion,
A load is applied to the support frame 31 in an upward direction in the drawing due to the reaction force of the pinion 32 that lowers the rack 30, and this load is applied as follows: shock pad 34 → lower common seat 37 → lower backing plate 38 → load converter 20 →
The force is transmitted from the upper backing plate 25 to the projection sheet 26 to the upper common sheet 39 to the jack house (top plate) 35, and becomes a force that pushes up the platform. In this way, this large load measuring device 27 is inserted between the load transmission paths, and the load converter 2
0, the projection 23, the upper backing plate 25, and the projection sheet 26.
A large load is applied to a relatively flexible member such as the top plate 28 (in this example, the weight of the platform is
4000t~20000t) can be measured with high precision. Thus, for example, when jacking up a platform, the proportion of the load on the several legs can be monitored, thereby preventing the risk of overturning. In particular, the legs adjust to the soft ground on the ocean floor,
Stabilization is extremely important, and methods of stabilization include pumping seawater into the platform and placing heavy weight on the legs, or
In order to concentrate the load on the remaining legs by lifting two legs, it is necessary to carefully operate while monitoring the load balance on the legs. The present invention is extremely suitable as a load measuring device in such a case.

In addition, although the above application example shows the case of a jack-up platform, it can also be applied to large load measurement for land, civil engineering, and construction without departing from the gist of the invention.

As described in detail above, according to the present invention, the height of the load measuring device as a whole is reduced as much as possible, the weight is small, the cost is reduced, and the structure is extremely strong against lateral loads. It is possible to provide a large load measuring device for steel structures, etc., which can measure with high precision large loads applied to relatively flexible members, such as steel structures, which have been considered difficult.

[Brief explanation of the drawing]

Figure 1 is a front view showing an example of a conventional load measuring device, and Figures 2 to 8 are diagrams for explaining problems when measuring loads on relatively flexible members such as steel structures. Figures 2 and 3 are a plan view and front view showing an example of a configuration in which a load converter is inserted between steel structures, and Figure 4 is a front view showing the deformation state of the steel structure under load. , Fig. 5 and Fig. 6 are diagrams showing the stress distribution state on the upper end surface of the load converter, and Figs. Figure 8 a and b are diagrams showing the stress distribution state of each part in the figure.
FIGS. 9, 10 and 11 are a front view showing a configuration example different from that shown in FIG. Fig. 12 a, b, c, and d are diagrams showing the stress distribution state in each part of the large load measuring device according to the present invention;
3, FIG. 14, and FIG. 15 are a plan view, a front view, and an enlarged view of the main parts in FIG. 14, showing an application example of the present invention. 20... Load converter, 21... Internal space, 22
... Upper end surface, 23 ... Annular protrusion, 24 ... Strain gauge, 25 ... Upper backing plate, 26 ... Protrusion sheet, 27 ... Large load measuring device, 28 ... Top plate,
29... Leg, 30... Rack, 31... Support frame, 32... Pinion, 33... Pinion drive device, 34... Shock pad, 35... Jacket house, 37... Lower common seat, 38... Lower Backing plate, 39... Upper common sheet.

Claims (1)

[Claims] 1 In a load measuring device that measures a large load applied to a relatively flexible member such as a steel structure using a load converter inserted between the load transmission path, the overall shape is cylindrical and the device that receives the load a load converter that has a ring-shaped protrusion on at least one of the end faces and converts a load applied to both end faces into an electrical quantity by a strain gauge attached to the peripheral surface; A steel plate characterized by comprising a caul plate that abuts one end surface having the protrusion of the load converter, and a cylindrical protrusion sheet that abuts or is integrated with the other side of the abutment plate. Large load measuring device for structures, etc.