Abstract:
The machine is used to automatically measure both the twist and concavity of agricultural discs with a high level of precision. Currently, in order to calculate such measurements, dial indicators are used to investigate whether twist and concavity variables are within pre-established tolerances. This conventional methodology is slow and imprecise. In order to measure twist and concavity according to the invention, the agricultural disc is rotated and data is recorded along the periphery of the disc using a laser measurement device, by means of which a previously recorded central reference point is also determined, by comparing the resulting values in terms of height.

Description:
OBJECT OF THE INVENTION 
       [0001]    The present invention, as expressed in this descriptive specification, relates to a machine and method for acquiring data for measuring the twist and concavity of agricultural discs. 
         [0002]    The machine is designed to measure both the twist and the concavity of agricultural discs, quickly and automatically, with a high level of precision, by means of a laser measurement device built into it. 
         [0003]    The twist and concavity of the agricultural discs are measured in order to comply with pre-established technical specifications, used to check the quality of the end product obtained. 
       BACKGROUND OF THE INVENTION 
       [0004]    At the moment, agricultural discs must be submitted to quality control tests once they have been manufactured. These tests check whether or not the agricultural discs manufactured comply with a number of pre-established technical specifications. 
         [0005]    The technical specifications to be revised include those related to twist and concavity at the disc surface. 
         [0006]    Currently, said specifications are usually measured manually by means of a dial indicator. This instrument is used to test twist and concavity, determining whether or not these variables fall within established tolerance levels. 
         [0007]    This method is very slow if large amounts of measurements are to be made, owing to the limitations posed by the agricultural disc fastener used to make said measurements. 
         [0008]    Likewise, the precision with which this method is carried out depends on the skill of the person using the dial indicator. 
       DESCRIPTION OF THE INVENTION 
       [0009]    With the aim of achieving the aims and avoiding the limitations set out above, the first object of the invention constitutes a machine for acquiring data for measuring the twist and concavity of agricultural discs, comprising:
       a rotational mounting bracket, upon which an agricultural disc is supported and held.   a hold-down plate free to rotate, arranged above the mounting bracket, both elements being opposite one another in the same vertical direction.   a linear actuator, which travels vertically in a downwards direction towards the hold-down plate, pressing the same down and butting against a central area of an upper surface of the agricultural disc placed on the mounting bracket, whilst in other positions above the hold-down plate, the same is distanced from the agricultural disc.   a laser measurement device, arranged above the agricultural disc to be measured, which in turn, is coupled to a linear guide arranged in a direction perpendicular to the vertical direction in which the hold-down plate travels, which coincides with the vertical direction around which the mounting bracket rotates.   a frame, upon which the various elements of the machine are supported.       
 
         [0015]    Once the agricultural disc has been immobilised and is held between the mounting bracket arranged below and the hold-down plate arranged above, said agricultural disc is made to rotate by means of the rotational activation of the mounting bracket. 
         [0016]    In one embodiment of the invention, the location of the agricultural disc comprises a space delimited by a rear protection surface, two side surfaces and a table platform, above which the mounting bracket protrudes. 
         [0017]    The table platform is joined to some legs, which form part of the frame of the machine, object of the invention. 
         [0018]    The hold-down plate forms part of a rotational head-piece, fixed to the rod of a vertical cylinder by means of a female sleeve, said vertical cylinder constituting the linear actuator for vertically displacing the hold-down plate. 
         [0019]    Moreover, the rotational head-piece comprises a lower fixation sleeve, upon which the hold-down plate is supported; an upper fixation sleeve, coupled to the female sleeve and; an intermediate axial load ball bearing, placed between both fixation sleeves. 
         [0020]    The intermediate ball bearing is housed in a hollow, delimited by an end annular recess in the female sleeve and by circumferential portions of both fixation sleeves, i.e., the upper and lower fixation sleeves, both being joined by means of screws. 
         [0021]    Said lower fixation sleeve has at least one built in appendix, wherein the hold-down plate is engaged, which is immobilised by means of a number of set screws, the ends of which fit in a number of blind grooves in the lower fixation sleeve appendix. 
         [0022]    The hold-down plate has a first built in annular stop, which presses against the upper face of the agricultural disc to be controlled, whilst the mounting bracket has a second built in annular stop, upon which the agricultural disc is supported on its lower face. 
         [0023]    The mounting bracket is built into an actuator device fixed to the machine frame and rotates as a result of being driven by a motor, also fixed to the machine frame. 
         [0024]    Said actuator device comprises a casing, fixed to the machine frame, which supports a vertical shaft that rotates as a result of being driven by the aforementioned motor, the mounting bracket being engaged in an upper end stretch of the vertical shaft, whilst said mounting bracket rests against an annular extension of the vertical shaft. 
         [0025]    Another characteristic of the invention is that the actuator device have ball bearings, interspersed in the coupling of the vertical shaft, relative to the casing of said actuator device. 
         [0026]    It must also be noted that the upper end of the vertical shaft of the actuator device has a housing built into its centre, in which a male element is engaged, where a central perforation of the agricultural disc is adjusted, in addition to a central perforation of a model disc, initially placed in order to determine a central reference point, as shall be described further on. 
         [0027]    A second object of the invention relates to a method for acquiring data for measuring the twist and concavity of agricultural discs. 
         [0028]    The method comprises the following stages:
       Placing the model disc in the centre of the mounting bracket.   Positioning the laser measurement device in a central area of the model disc, above the same.   Rotating the model disc, in order to use the laser measurement device to obtain reference data, corresponding to points at an equal distance away from the centre of the model disc, in order to determine a central reference height corresponding to said centre of the model disc. These points are measured relative to a start point in the machine located such that it corresponds with the laser device, taking the height between each one of said points relative to the start point cited into account.   Once the central reference height has been determined, the model disc is dismounted and the process for measuring the agricultural discs continues, each agricultural disc to be measured being mounted in the centre of the mounting bracket, ensuring the same is immobilised by means of lowering the hold-down plate.   The laser measurement device is displaced, in order to be positioned such that it corresponds with the periphery of the agricultural disc.   Measurements are made in order to obtain data (at points along the perimeter) along the perimeter of the agricultural disc, as the same rotates, using the laser measurement device.   Both the twist and concavity of the agricultural disc are calculated using the measurement data acquired.       
 
         [0036]    The twist of the agricultural disc calculated corresponds to the difference in height between the maximum and minimum measurements acquired in the data, this measurement data corresponding to the heights measured from the start point of the laser measurement device and 1 the points chosen along the periphery of the agricultural disc, when opposite said start point in the laser measurement device, height values thereby being obtained. 
         [0037]    The difference in height between the resulting values obtained is subsequently compared against pre-established tolerance limits, in order to determine whether or not the agricultural disc is valid in terms of twist. 
         [0038]    Concavity is measured in accordance with diametral axes in each agricultural disc, in such a way that concavity is calculated taking the measurement data corresponding to height, acquired between several pairs of diametrically opposed peripheral points on the agricultural disc, relative to the start point, into account, in addition to the height of the central reference point. 
         [0039]    The following are calculated in accordance with each diametral axis: a first distance between the start point of the laser measurement device and a point along the periphery of the agricultural disc and; a second distance between the start point of the laser device and a diametrically opposed point of the agricultural disc periphery. These distances constitute vertical magnitudes (heights). 
         [0040]    The average between the first and second distances is subsequently calculated and said average is then compared to the central reference height of the model disc, the difference between both constituting the concavity of said axis. 
         [0041]    Finally, the average of the concavities of the axes measured is found and compared with pre-established tolerance levels, in order to determine whether or not the agricultural disc is valid in terms of concavity. 
         [0042]    The reference data pertaining to the model disc is obtained as follows:
       A first piece of data is taken prior to setting the model disc into rotational motion.   A second piece of data is taken as the agricultural disc moves rotationally at 0.9 seconds.   A third piece of data is taken at 1.8 seconds, keeping the agricultural disc in rotational movement.   A fourth piece of data is taken at 2.7 seconds, keeping said agricultural disc in rotational motion.       
 
         [0047]    The measurement data (points) chosen along the periphery of the agricultural disc are taken by rotating the agricultural disc by one full turn, plus a portion of a second turn, with a time interval of at least 0.001 seconds. 
         [0048]    Of the measurement data obtained, a few pieces of specific data are chosen, in order to calculate concavity, these pieces of data being chosen as follows:
       A first piece of data, which is chosen at 0.8 seconds after beginning to rotate the agricultural disc.   A second piece of data, collected at 1.465 seconds.   A third piece of data, collected at 2.13 seconds.   A fourth piece of data, collected at 2.795 seconds.   A fifth piece of data, collected at 3.46 seconds.   A sixth piece of data, collected at 3.325 seconds.       
 
         [0055]    Below, in order to facilitate better understanding of the present descriptive specification, a number of drawings are attached, which form an integral part of the same and provide a non-limiting illustration of the object of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0056]    FIG.  1 .—Is a perspective view of the machine for acquiring data for measuring the twist and concavity of agricultural discs. 
           [0057]    FIG.  2 .—Is a cross-section of a rotational head and hold-down plate assembly. 
           [0058]    FIG.  3 .—Is a cross-section of an actuator device, with a built-in vertical shaft, the upper end of which is fixed to the mounting bracket, the assembly formed by said vertical shaft and the mounting bracket being rotated by means of a motor. 
           [0059]    FIG.  4 .—Is a plan view of a model disc, initially used to identify a central reference point. 
           [0060]    FIG.  5 .—Is a plan view of an agricultural disc with various reference points around the perimeter. 
           [0061]    FIGS.  6  and  7 .—Are schematic views providing a basic representation of the system for measuring twist and concavity, by taking data at the periphery of the agricultural disc, in addition to a central reference point that corresponds to the centre of said agricultural disc. 
       
    
    
     DESCRIPTION OF AN EXEMPLARY EMBODIMENT OF THE INVENTION 
       [0062]    The machine for acquiring data for measuring the twist and concavity of agricultural discs comprises the following elements, listed according to the numbering adopted in the drawings:
     1 .—Frame     2 .—Vertical cylinder     3 .—Hold-down plate     3   a .—First annular end     4 .—Linear guide     5 .—Laser measurement device     6 .—Table platform     6   a .—Hole     7 .—Actuator device     8 .—Motor     9 .—Rear protection surface     10 .—Side protection surface     11 .—Side protection surface     12 .—Legs     13 .—Mounting bracket     13   a .—Second annular end     14 .—Rod     15 .—Female sleeve     15   a .—End annular recess     16 .—Intermediate ball bearing     17 .—Upper fixation sleeve     17   a .—Circumferential portion     18 .—Lower fixation sleeve     18   a . Circumferential portion     19 .—Screws     20 .—Appendix     20   a .—Blind grooves     21 .—Rotational head-piece     22 .—Set screws     23 .—Vertical shaft     23   a .—Annular extension     24 .—Casing     25 .—Ball bearings     26 .—Housing     27 .—Male element     28 .—Agricultural disc     28   a .—Central perforation     29 .—Model disc     29   a .—Central perforation   
 
         [0102]    In principle, it comprises a frame  1 , a rear protection surface  9  and two side protection surfaces  10 - 11 , which define a frontally open surrounding space. 
         [0103]    A vertical cylinder  2  is installed in the upper area on said frame  1 , which may be pneumatic or hydraulic and is responsible for driving a hold-down plate  3  that forms part of a rotational head-piece  21  connected to the rod  14  of the vertical cylinder  2  by means of a female sleeve  15 , which threads onto said rod  14 . Likewise, a linear guide  4  is fixed onto said frame  1 , upon which a laser measurement device  5  is displaced. 
         [0104]    Furthermore, the machine has a table platform  6  supported by means of legs  12 , said legs  12  in turn being supported on the machine frame  1  itself. 
         [0105]    An actuator device  7  is mounted to the lower portion of this frame  1 , a mounting bracket  13  protruding from said actuator device  7  through a hole  6   a  made in the table platform  6 . 
         [0106]    The female sleeve  15  has an end annular recess  15   a , in which an intermediate axial load ball bearing  16  is inserted, the same being held by means of using two fixation sleeves, namely an upper  17  fixation sleeve and a lower  18  fixation sleeve, both being joined by means of screws  19 . 
         [0107]    Said intermediate ball bearing  16  is housed in a hollow delimited by the end annular recess  15   a  in the female sleeve and by circumferential portions  17   a  and  18   a  of both fixation sleeves, namely the upper  17  and lower  18  fixation sleeves, respectively. 
         [0108]    The lower fixation sleeve  18  has an appendix  20  to which the hold-down plate  3  is coupled by means of screws  22 , the ends of which fit into a number of blind grooves  20   a  in the appendix  20  of the lower fixation sleeve  18 . 
         [0109]    The rotational head-piece  21  in turn comprises the two fixation sleeves, i.e. the upper  17  and lower  18  fixation sleeves, alongside the hold-down plate  3 . 
         [0110]    In turn, the actuator device  7  is formed by a casing  24 , which is fixed to the frame  1 . Inside said casing  24 , there is a vertical shaft  23 , supported by ball bearings  25 . In correspondence with the lower end of the vertical shaft  23 , a motor  8  is coupled, which provides said vertical shaft  23  and as such, the mounting bracket  13 , with rotational movement. 
         [0111]    In contrast, the upper end of the vertical shaft  23  is inserted into the mounting bracket  13 , which has a housing  26  at its centre, in order for a male element  27  to be inserted therein, where a central perforation  28   a  of the agricultural disc  28  to be measured is adjusted, a perforation  29   a  of a model disc  29  initially placed on the mounting bracket  13  also being adjusted. 
         [0112]    It must also be noted that the mounting bracket  13  is supported against an annular extension  23   a  of the vertical shaft  23 . 
         [0113]    Having sufficiently described the structure of the machine, object of the invention, we shall now go on to describe how said machine works. 
         [0114]    The agricultural disc to be measured is inserted into the male element  23 , whilst it is supported against the mounting bracket  13 . The vertical cylinder  2  is subsequently driven, the hold-down plate  3  therefore being lowered until an annular stop  3   a  of said hold-down plate  3  comes into contact with the agricultural disc  28 , fixing it against the mounting bracket  13 . 
         [0115]    The motor  8  drives the rotation of the vertical shaft  23 , also making the mounting bracket  13  rotate jointly and, the hold on the agricultural disc  28  provided by the hold-down plate  3  onto said mounting bracket means that activating said motor  8  also causes the rotational head-piece  21  assembly including the hold-down plate  3  to be pulled. 
         [0116]    The laser measurement device  5  takes data measurements as the agricultural disc  28  rotates. 
         [0117]    The data taken by the laser measurement device  5  is stored in a PLC, in order to subsequently calculate the twist and concavity of the agricultural disc  28  using a computer program, thereby checking whether or not said agricultural disc  28  complies with the required specifications previously set down. 
         [0118]    Should the disc fall within the required tolerance limits, the machine will emit a green light, whilst if it does not, the same will emit a red light. 
         [0119]    The method for acquiring data for measuring the twist and concavity of agricultural discs is as follows: 
         [0120]    Firstly, at the start of the day, a central reference height is measured using the model disc  29 , in accordance with a central point “X” on said model disc  29 . 
         [0121]    In order to do so, the laser measurement device  5  is positioned via the linear guide  4 , such that it corresponds with the central area of the model disc  29  fitted onto the male element  27  by means of its central perforation  29   a , the hold-down plate being kept in an upper position. 
         [0122]    In said position, the model disc  29  is made to rotate and reference data corresponding to four points a-b-c-d at an equal distance from the centre of said model disc  29  are taken, in order to determine the central reference height. Said points are measured relative to a start point “Z” in the machine, located such that it corresponds with the laser measurement device  5 , the heights between each one of said points relative to said start point “Z” being taken into account, the average value of said heights corresponding to said reference data subsequently being calculated, in order to thus obtain the central reference height of the model disc  29 . 
         [0123]    Said reference data is acquired as follows:
       a first piece of data “a” is taken before beginning to rotate the model disc  29 .   The model disc  29  is then set into rotational motion.   A second piece of data “b” is taken at 0.9 seconds.   A third piece of data “c” is taken at 1.8 seconds.   A fourth piece of data “d” is taken at 2.7 seconds.       
 
         [0129]    Once the central reference height has been calculated, the model disc  29  is dismounted and each agricultural disc  28  to be measured is mounted, a number of pieces of measurement data being taken for the different agricultural discs  28  to be measured, in order to calculate the twist and concavity, this measurement data corresponding to the heights measured from the start point “Z” of the laser measurement device  5  and each one of the points along the periphery of the corresponding agricultural disc  28 . 
         [0130]    In order to calculate concavity and twist, the laser measurement device  5  is displaced via the linear guide  4  to the periphery of the agricultural disc  28  to be measured, where it will collect data corresponding to the periphery (points along the perimeter) of said agricultural disc  28  at very short time intervals of at least 0.001 seconds. 
         [0131]    Of the data acquired in previous steps, six pieces of measurement data corresponding to specific points (A, B, C, D, E and F) are used to calculate concavity, which correspond to three diametral axes of the agricultural disc  28 : A-D, B-E and C-F. 
         [0132]    When the agricultural disc begins to rotate, 0.8 seconds pass without collecting or taking data. Subsequently, the data used to calculate concavity is collected as follows, as the agricultural disc  28  is in rotational movement:
       Data “A” is collected at 0.8 seconds after beginning to rotate the agricultural disc  28 .   Data “B” is collected at 1.465 seconds.   Data “C” is collected at 2.13 seconds.   Data “D” is collected at 2.795 seconds.   Data “E” is collected at 3.46 seconds.   Data “F” is collected at 3.325 seconds.       
 
         [0139]    Once the laser measurement device  5  has collected the last piece of data, the agricultural disc  28  continues to rotate for a further 1.465 seconds, until the hold-down plate  3  is lifted. 
         [0140]    All of the data is collected by rotating the agricultural disc  28  by one full turn, plus a portion of a second turn on the mounting bracket  13 . 
         [0141]    The laser measurement device  5  collects data as follows: a laser diode emits a beam, which crosses an emitter lens and crashes against the upper surface of the agricultural disc  28 . The beam reflected from the agricultural disc  28  is subsequently collected by a reflective lens and sent to a sensor, which detects the intensity peak, thereby establishing the distance from the agricultural disc  28 . 
         [0142]    The twist of the agricultural disc  28  is calculated in accordance with the data collected and corresponds to the difference in height (the direction perpendicular to the plane of said agricultural disc  28 ) between the maximum and minimum values of all the measurement data acquired along the periphery of the agricultural disc. 
         [0143]    In contrast, the concavity of the agricultural disc  28 , in accordance with the data collected, is calculated as follows: 
         [0144]    First of all, in one embodiment of the invention, the concavity of three diametral axes of the agricultural disc  28  are calculated: 
         [0000]    
       
         
           
             Concavity 
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         [0000]    where “X” refers to the central reference point of the model disc  29 , whilst “Z” refers to a start point at coordinates of the machine located such that they correspond with the laser measurement device  5 , the distance (ZX) constituting the central reference height. 
         [0145]    The concavities of the three axes is then measured, thereby obtaining the concavity of the agricultural disc. 
         [0146]    Said values, corresponding to both concavity and twist, are comparted with their respective tolerance values, thereby deciding whether or not the piece is acceptable. 
         [0147]    As such, the machine and measurement method object of the invention reduce testing time (the time it takes the disc to complete one full turn) and increase precision, given that said testing does not rely on human ability. 
         [0148]    Furthermore, using the data acquired, it is possible to check whether or not the manufacturing process employed to make the agricultural discs complies with the desired technical specifications. 
         [0149]    As such, using the corresponding formula, it is possible to obtain short-term capacity indices, which indicate how suitable the manufacturing process is.