Abstract:
A device for measuring the torque or force exerted by a drilling machine during a rotation, driving or lifting of a tool. The measuring device includes an engaging device with a drilling battery or with a shaft of at least a drilling equipment or rotary of the machine the engaging device is susceptible of symmetrically or axial-symmetrically locking the drilling battery or the shaft preventing the rotation and/or the axial displacement in a position in correspondence to the tool. The engaging device is associated with at least a transducer for the detection of at least a maximum torque or of at least a maximum force exerted by the machine; and the measuring device is fixedly constrained to the drilling battery or to the shaft.

Description:
This application claims benefit of Serial No. TO 2010 A 000871, filed 2 Nov. 2010 in Italy and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed application. 
     BACKGROUND 
     The present invention concerns a measuring device and in detail it concerns a device for measuring the torque of a rotation drilling machine or for measuring the force exerted by a drilling, driving or lifting machine on a tool. 
     It is known that machines for excavating or drilling the ground comprise devices that are commonly called rotary, for the transmission of the torque to a drilling battery at the end of which an excavation or drilling tool which typically rotates is engaged. The drilling battery typically comprises—in a non exhaustive manner—drilling rods, tubes or blades. 
     The rotary is moreover engaged so as to slide along a load-bearing structure, which is commonly called antenna; through suitable systems known in the field a pushing or pulling force is exerted onto the rotary and consequently to the drilling battery and therefore to the tool. 
     In the field of drilling machine tools, in recent years it has become a common requirement to have a performance that is always greater in terms of depth and excavation diameters obtained. This directly reflects onto the performances in terms of torque and pull-push of the machines. Consequently it is important to be able to certify and demonstrate their actual performances. The present finding concerns a device for carrying out rapid and reliable measurements of the maximum torque and pull-push that can be delivered. 
     From JP58098511 a device is known for measuring the dynamic torque exerted by a motor on a shaft. In particular, the device described in JP58098511 is positioned between a motor and a speed reduction unit, and does not therefore carry out a reading of the torque of a tool. Moreover, said device is a device that is integrated in a machine, and cannot therefore be used to carry out test measurements in series. 
     From U.S. Pat. No. 3,589,179 a device with a single arm is known for measuring the torque on drilling rods. Said device uses a compression load cell that is mounted at one end of a single arm held by a line. Said line is connected to a winch. 
     The device described in U.S. Pat. No. 3,589,179 is characterised in that it has the drawback of having a single measuring arm; said arm does not allow a symmetrical measurement of the torque and, in order to balance the force on the load cell, a force is created on the battery of rods which tends to flex it causing possible damage to the battery itself or wrong measurements. 
     Moreover, the device described in U.S. Pat. No. 3,589,179, is not adapted for measuring also load forces which are axially oriented with respect to a direction in which the excavation or drilling is being carried out. Furthermore, the patent does not describe how to dispense the maximum torque available and how to usefully oppose it. This is a critical problem in the case in which very high torque values are measured. 
     Finally from EP0640743 a device is known for measuring the dynamic torque on a drilling tool, or bit. Said device also measures a weight on the tool itself, and the extensometric cells which it is provided with are positioned inside radial holes that are obtained on elements of the drilling battery near to the tool itself, thus remaining constantly mounted. 
     Said device is not adapted for being used for testing in series adapted for detecting the torque or the maximum force that can be exerted by an excavation or drilling machine. It is, indeed, a device that is integrated with the excavation tool which does not therefore make it possible for the machine to dispense the maximum torque or pull-push. It is also very complex due to the need of having an electric rotary joint so as to transfer the signal from the rotating part to the part that is fixed to the machine. It also requires systems for compensating for temperature variations, action of the excavation fluids and effect of the flexing of the battery of rods during the excavation. All these characteristics are necessary for a device that carries out a measurement during drilling but are not useful for a testing device. 
     SUMMARY 
     The purpose of the present invention is therefore that of describing a measuring device which does not have the aforementioned drawbacks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention shall now be described with reference to the attached drawings, which illustrate an embodiment given as an example and not for limiting purposes, in which: 
         FIG. 1  illustrates an overall view of a drilling machine to which a measuring device according to the present invention is associated. 
         FIG. 2  illustrates a detail of the device of  FIG. 1  in a first embodiment thereof; 
         FIG. 3  illustrates a chart of the trend of the torque as a function of the rotation angle obtained through the use of the device for measuring the torque object of the present invention. 
         FIG. 4  illustrates a detail of the device of  FIG. 1  in a variant thereof; 
         FIGS. 5   a  and  5   b  represent the measuring device object of the present invention mounted on a test bench; 
         FIG. 6  illustrates a chart of the pressure and consequently of the force as a function of the angle of rotation that can be obtained through the measuring device object of the present invention mounted on the test bench of  FIGS. 5   a ,  5   b;    
         FIG. 7  illustrates a detail of the device of  FIG. 1  in a second embodiment thereof; and 
         FIG. 8  illustrates a detail of a third embodiment of the device object of the present invention; 
         FIGS. 9   a ,  9   b  represent a detail of an alternative embodiment of a part of the measuring device illustrated in the previous  FIG. 8 ; 
         FIG. 10  illustrates a detail of a fourth embodiment of the measuring device object of the present invention; and 
         FIG. 11  illustrates an alternative embodiment that is common to all the identified variants. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , a device for measuring the torque or the force exerted by an excavation or drilling machine on an excavation or drilling tool, is wholly indicated with reference numeral  200 . 
       FIG. 1  represents an excavation or drilling machine  100 , comprising an antenna  101  on which a rotary  102 , or drilling equipment, is guided and moved, designed so as to transmit a rotation torque to at least one drilling rod  102   a , usually made as a battery  103  of drilling rods  102   a , to which an excavation or drilling tool  104  is generally engaged (not shown). 
     Device  200  for measuring the torque is connected to a drilling rod  102   a , or like in the case of  FIG. 4  directly to the shaft of rotary  102  of said machine, by means of engaging means  201  which in the first embodiment represented in  FIG. 1  comprise a central cylindrical element, that is capable of blocking drilling rod  102   a  or shaft  110  of the rotary thus preventing it from rotating. 
     In the first embodiment of  FIG. 1 , device  200  is engaged with a plate  300  which is fixed to the ground or blocked by the weight of machine  100  itself. 
     Device  200  also comprises a torque or force transducer, which in the first embodiment is a load cell  203 , which is capable of transforming the force or torque (in this case indirectly) measured in an electrical signal that is susceptible of being read by a tester or more generally by an electric/electronic measuring tool  500  that is capable of showing a user a quantitative measurement of the torque or force exerted by rotary  102  at an excavation or drilling tool, and i.e. at the end part of drilling rod  102   a  or of the shaft. 
     Said engaging means  201  also comprise a plurality of arms  202   a ,  202   b , in the figures shown as two, having a first end engaged with central cylindrical element  201  and a second end to which load cell  203  is connected, which in turn is fixed to an abutment  205 , which is fixed to plate  300 . 
     In particular, one of the two arms  202   a ,  202   b , has, for all purposes, connected load cell  203 , whereas the opposite one is equipped with a simple pin  204  for connecting with abutment  205 . 
     When it is necessary to carry out a measurement of the maximum torque that can be delivered by drilling equipment  102 , it is firstly necessary to disassemble possible drilling tool  104  connected to battery  103  of drilling rods  102   a , and thus mount device  200  as previously described. 
     Subsequently, it is necessary to make excavation equipment  102  dispense the maximum torque available, and this is indeed possible through the capability of blocking device  200  object of the present invention, which blocks the rotation of battery  103  or of the shaft of the motor creating a resistant load which is, in any case, greater with respect to the maximum torque that can be delivered by drilling equipment  102 . The torque is thus transferred to abutment  205  through the two arms  202   a ,  202   b  and it is thus transformed into two forces with equal value and opposite sign, one of which is detected by the load cell  203 . 
     Therefore, said load cell  203  is built in a way such as to detect a force acting in a direction that is perpendicular with respect to the direction of the rotation axis of battery  103  of drilling rods  102   a.    
     Starting from the fact that the length of one lever arm  600  is known, since it can be read on a plurality of reference points  601  located on arm  202   a , it is possible to read directly, alternatively or in combination, on the tool the force value just as well as the torque value delivered by drilling equipment  102 . Also pin  204  can be instrumented. 
     In the case in which it is desired to introduce a second load cell  203  also on arm  202   b , it is sufficient to connect them both in parallel so as to directly have an average signal of the two values. 
     The fact that there are two load cells can lead to the advantage of having reading redundancy of the torque or force values exerted by the machine and if there is a possible error in the measurements by a load cell due to a non perfect symmetry of the measuring device caused by the manufacture tolerances, it would be averaged out by the reading on the second one. 
     Device  200  is subject to measuring many torque levels; indeed, on each of arms  202   a ,  202   b  there is a plurality of holes  202   c  on which load cell  203  and pin  204  can be selectively arranged. Clearly, load cell  203 , just as pin  204 , must be positioned in the same holes of respective arm  202   a ,  202   b  so as to have a symmetrical torque distribution; indeed, purely as an example, if load cell  203  is positioned in the second last hole  202   c   1 , then also pin  204  will be positioned in the second last hole  202   c   2  on arm  202   b  opposite with respect to that on which load cell  203  is mounted. 
       FIG. 2  represents an elastic element  211  which is part of measuring device  200 . The elastic element allows drilling battery  103  to rotate by a few degrees before being completely blocked. This device is necessary in the case in which rotary  102  is made with motors having a non maximal performance when in stall mode. Therefore, when there are motors of this kind, when in stall mode, there is in reality a reading of the torque which is lower than the maximum torque which can actually be obtained. By using this elastic element  211 , therefore, electric/electronic measuring tool  500  reads a small peak which is the maximum torque value at a dynamic behaviour of the motor. The measuring method described here, is thus defined as “almost static”, since at a first and brief dynamic step, in which typically the drilling rod or shaft do not even carry out a full rotation, there is then, in any case, a stalling step. 
     In other words, the elastic element forms the static ending block due to a torque or force action equal and opposite with respect to said force or torque exerted. Elastic element  211  can be, as an example and not for limiting purposes of the type with compression traction means, torsion springs, hydraulic springs or rubber elements. 
       FIG. 3  shows a diagram that can be obtained with measuring device  200 , in which M, in the ordinate, indicates the torque delivered by the rotary and α, in abscissa, is the rotation angle of the battery. Through measuring tool  500  it is thus possible to obtain a series of data of the torque delivered by rotary  102  and to correlate them to the rotation angle of the battery. With certain types of motors a diagram is thus obtained of the type indicated with line  1  (continuous line), which has a peak before the stopping of the motor which is obtained when in stall mode. With other types of motors that do not have this problem a trend type  2  (broken line) will be obtained. The tester type instrument means also make it possible to record the data acquired by the load cells and to reprocess them through a personal computer. In this way it is also possible to evaluate and compare the performances in stall mode and the dynamic performances of the motor used and of the overall system. 
     As illustrated in  FIG. 4 , device  200  object of the present invention can also be used to carry out measurements on the pull-push of drilling machine  100 . The embodiment of device  200  shown in  FIG. 3  differs from that identified and described in  FIGS. 1 and 2 , respectively, only for the fact that arms  202   a ,  202   b  are rotated by 90° with consequent rotation also of load cells  203 . 
     In this case, in addition to abutment  205 , device  200  also comprises a pair of upright elements  205   a ,  205   b , each fixed to abutment  205 ; said upright elements  205   a ,  205   b  avoid the interference between the lower part of engaging means  201  and abutment  205  itself. 
     Also in this case, since there two arms, load cell  203  undergoes only half of the force load which can be exerted by machine  100 . 
     Alternatively, it is however possible to make device  200  operate with a single load cell  203 ; in said case it will be fixed to a plurality of holes  205   c  present on abutment  205 , in a position in axis with engaging means  201  and, consequently, in axis with the load to be measured. Abutment  205  is, in any case, designed with a dimension that is sufficient so as to avoid flexing that is capable of distorting the measurement of the load. 
     Also during this use it can be advantageous for there to be elastic element  211 , especially if the pull-push is obtained through a catenary and with types of geared motors which have performances that are greater in dynamic behaviour than in static behaviour. 
     Elastic element  211  can thus operate in torsion and in traction compression. 
       FIG. 5  indicates measuring device  200  in a configuration for measuring torque mounted on testing equipment  350 . This equipment comprises a support  300 , which could be a plate like that which was previously described on which machine  100  can be mounted and locked in place with its own weight. Measuring device  200  is mounted on a pin  301  fixed on support  300  and has the possibility of rotating around the axis of this pin. There is also an instrumented jack  310  which regulates the rotation of device  200 . 
     The hydraulic system of the jack comprises a pressure transducer  311  and a pressure regulator  312 . With this equipment, by regulating pressure with  312  it is possible to create a gradual stall torque at rotary  102  and make a complete curve which completely characterises its behaviour. 
     With this almost static system it is thus possible to make a torque-rotation speed curve that is typically obtained with complex dynamic systems. Jack  310  has a sensor inside it which makes it possible to know its stroke. Based upon this stroke and on the geometrical relations which correlate the lever arm d of the jack to the length itself of the jack it is always possible to find the torque delivered by rotary  102  even indirectly from the pressure readings of jack  310  itself. 
     The reaction force of the jack is indeed known once its operation pressure and bore are known. Diagrams of the type of  FIG. 6  are thus found in which P indicates the pressure of the jack and a indicates the rotation angle of the battery. In this way it is also possible to carry out a comparison between the reading of torque obtained with device  200  and the reading with test bench  350 . 
     Jack  310  can technically carry out the same function as elastic element  211 . 
       FIG. 7  shows a second embodiment of device  200 ; in said second embodiment there is no longer abutment  205 ; engagement means  201  are, on the other hand, fixed, through a plurality of brackets, directly to drilling equipment  102 . Therefore, in the second embodiment, the maximum torque delivered by drilling equipment  102  unloads straight onto the equipment itself. 
     More precisely, on a frame  102   a  of drilling equipment  102  on which two removable elements  207  are installed, operating as supports for load cell  203  and for pin  204 , which are mounted on a respective arm  202   a ,  202   b , exactly of the type described in the first embodiment of device  200 . 
     The second embodiment does not therefore need abutment  205 , but it can be installed directly on the excavation or drilling machine. 
     Also in this embodiment there can be an elastic element, which is not represented, with the advantages previously described. 
       FIG. 8  illustrates a third embodiment of device  200  object of the present invention. In this case the device exploits the same antenna  101  of the machine so as to deliver the maximum torque to the rotary. 
     A support element  212 , which is in turn engaged with an interface element between device  200  and antenna  101  of machine  100  is also coupled with central element  211 . 
     In this case the device is simplified, and it can carry out the measuring of the torque in a single rotation direction since shaft  214  comes into contact with load cells  203  and  204  through a cylindrical surface and only on one side. 
     A different embodiment which obviates the measurement problem as such, is the one that takes into consideration the disassembly of the two flanged supports which carry load cells  203  and  204  and their inversion. 
     The distance between the load cells is in this case fixed and a distance of a meter can be advantageously used so that the force read by the load cell has the same numeric value as the torque. The reading can thus be made with a tester which is not programmed and that is more cost-effective. 
     As a further variant elastic elements  215  are represented made in this case like buffers in elastic material, with the same function as the element previously described  211 . In this case they are placed between antenna  101  and an adapting support  213 . 
     A variant of elastic elements  215  is represented in  FIG. 9   a  and in  FIG. 9   b ; in said case, elastic elements  220  comprise two springs of compression type  221  and some cup springs  222 . There are at least two elastic elements  220  on each side. 
     When a measurement of the torque is carried out with device  200  object of the present invention, there is a first compression of the more yielding helicoidal springs and when spacer  223  of elastic elements  220  comes into contact with the much stiffer cup springs  222 , a resistant load is obtained such as to deliver the maximum torque to the rotary. 
       FIG. 10  shows a further variant of device  200  in which the retroaction on the antenna itself of the machine is exploited once again. 
     Device  200  in its fourth embodiment also comprises torque transducer means which this time comprise a torsion sensor or torque meter  210 , axially engaged with said cylindrical element  208  by means of a gear transmission box  209 , which is particularly useful if machine  100  is able to dispense particularly high torque. The purpose of gear transmission box  209  is thus that of sending a lower torque to torque meter  210 , so as to tackle a possible lack of transducer means that are capable of detecting the maximum direct torque actually delivered by equipment  102  to the tool. 
     If it is necessary to carry out a measurement of the maximum torque that can be delivered by drilling equipment  102 , it is necessary first of all to dismount the possible drilling tool  104  (not represented in the figures) connected to battery  103  of drilling rods  102   a , and thus mount device  200  as previously described. 
     Subsequently, it is necessary to make excavation equipment  102  dispense the maximum torque available, and this is possible indeed through the capability of blocking device  200  object of the present invention, which blocks the rotation of battery  103  or of the motor shaft creating a resistant load that is in any case higher with respect to the maximum torque which can be delivered by drilling equipment  102 . The torque is thus transferred to torque meter  201  through the second cylindrical element  208 , and through gear transmission box  209 . 
       FIG. 11  represents a form of use which can be common to all the variants indicated so far. It is possible to mount on an antenna  101  or analogous support two identical rotaries  102 A and  102 B and place device  200  between these. In this way it is possible to carry out a complete dynamic test creating a gradual load with one of the two rotaries passing from low torque and high number of revs to high torque and low number of revs until stalling. In said way it is however necessary to provide measuring device  200  with a rotary electric joint to bring the signal of load cells  203  or of torque meter  210  out from the rotating part. 
     The advantages of device  200  object of the present invention are known in light of the previous description. In particular, it makes it possible to deliver and measure a maximum torque as well as a pull-push force exerted by a drilling machine at its excavation or drilling tool. 
     The measuring device object of the present invention also makes it possible through the use of elastic elements  211 ,  215 ,  220  to carry out torque and pull-push measurements that are almost static, which when there are certain types of motors are much more precise than the single static measurements keeping the system cost-effective. 
     There is thus the advantage of having a system that is very precise and simple which does not require there to be sliding electrical contacts to bring the signals read from the rotating part to the tester. This, on the other hand, is required in dynamic reading systems. Therefore, said device provides true information about how much torque or force is really available to the tool, i.e. how much torque or force can then be actually transferred to the ground during the drilling. 
     The measurement of the rotation torque of the excavation tool occurs in a symmetrical or axial-symmetrical manner thus eliminating problems of flexing of the batteries of rods with consequent damage thereof and measurements that are not precise. 
     The device object of the present invention, finally, is not directly installed on the drilling or excavation machine but, on the contrary, it is independent; consequently it is particularly effective as a tool for testing or measuring the maximum torque or forces of pull or push on a plurality of drilling or excavation machines. Its most appropriate application is therefore testing drilling or excavation machines, although said application should not be considered limiting since it is just as possible to use device  200  object of the present invention even to verify possible problems present on the machine itself. 
     Particularly advantageous is the possibility of being able to feedback the torque on the antenna of the machine or on the rotary itself, since this action requires the sole use of the device of the present invention to carry out the torque measurement without requiring other equipment. 
     Finally, it is just as useful to be able to have a representation of a diagram showing the force or torque exerted by the rotary, in which it is possible to see both maximum value and the shape of the torque and force curve as a function of a load applied by the motor or of the rotation angle, thus making it possible to analyse a plurality of torque or force values that are even different from the maximum value. 
     Device  200  described so far can be modified with variations, modifications and additions, which are obvious to a man skilled in the art without for this reason departing from the scope of protection provided by the attached claims.