Abstract:
The invention relates to a measuring device for measuring the length of elongated profiles ( 100, 101, 102, 103 ) disposed in a longitudinal direction, particularly of pipes, between at least two opposing measuring sides ( 2, 3 ), of which at least one can be displaced on a measuring side ( 2, 3 ) in the longitudinal direction (L) until both ends ( 110, 111, 112, 113; 120, 121, 122, 123 ) of the elongated profile ( 100, 101, 102, 103 ) come in contact with each other, and at least one of the measuring sides ( 2, 3 ) has at least one measuring ram ( 10, 11, 12, 13 ), comprising at least two ribs ( 51   a,    51   b,    52   a,    52   b ) that extend at a distance to each other transversely to the longitudinal direction (L) and can be displaced elastically back and forth in the longitudinal direction (L).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a National Phase application based on International Application Serial No. PCT/DE2008/000205 filed Feb. 6, 2008, which claims benefit of priority of German Patent Application No. 10 2007 008 887.8 filed Feb. 21, 2007. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a measuring device for measuring the length of elongate profiles arranged in a longitudinal direction, in particular pipes, between at least two measuring legs located opposite one another. 
     2. Background Art 
     Measuring devices for measuring the length of pipes have long been known in the prior art. 
     In DE 430 82 83 C2, a measuring device is described which makes it possible to measure the length or other dimensional criteria of a pipe. In said document, measuring inserts are arranged in an exchangeable manner on the device. 
     In U.S. Pat. No. 3,975,829, a measuring device is described which makes it possible to check the dimensioning of a workpiece. In said document, a measuring head is provided which can be returned via a spring and which is hydraulically damped. 
     The disadvantages of the above-described measuring devices are the multiple-component structure and the associated wear phenomena and also more frequent maintenance work. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to provide a measuring device of the type mentioned in the introduction which is composed of a relatively small number of components. 
     This object is achieved by a measuring device of the type mentioned in the introduction which has the features of the main claim. 
     To this end, the measuring device according to the invention comprises two spaced-apart measuring legs, at least one of which is displaceable. 
     Preferably, the displaceable measuring leg is connected to a distance meter which makes it possible to determine roughly the distance between the two measuring legs. 
     In order to determine precisely, i.e. to an accuracy of 0.4 μm, the length of an elongate profile, in particular a hollow or solid metal profile, it is provided a according to the invention to provide memory rams in at least one of the measuring legs. Preferably, all of the measuring rams are arranged in one of the two measuring legs, most advantageously in the displaceable measuring leg, so that the measuring electronics can be accommodated at one location. 
     The measuring device also allows the simultaneous, highly precise measurement of a plurality of profiles, and to this end a number of measuring rams corresponding to the plurality of profiles is provided. Preferably, the displaceable measuring leg comprises two, three or four measuring rams. 
     Each of the measuring rams is preferably formed in one piece and collaborates with a measuring sensor assigned thereto. The measuring ram has in each case one contact tongue, two webs and one movable and one positionally fixed spacer section. One positionally fixed section can be assigned to a plurality of, in particular two, adjacent measuring rams. 
     As a result of pressure being exerted by one end of a profile on one of the contact tongues, the latter is pushed into the measuring leg somewhat, in particular by less than 1 mm. The pushing-in of the contact tongue results in the deformation of two webs which are both arranged essentially parallel to the contact tongue and which are likewise connected in one piece with the contact tongue via the respective movable spacer section. 
     A first end of the two webs is integrally connected to the positionally fixed spacer section, and a second end of the two webs is integrally connected to the movable spacer section. 
     The arrangement according to the invention corresponds kinematically to that of a four-joint transmission. Correspondingly, a respective articulation would be arranged at the four transition points where the webs meet the spacer sections. 
     By contrast, the embodiment as a one-piece integral component according to the invention is particularly low on wear, maintenance-free and can be produced with high precision by means of the wire erosion process. The measuring ram is preferably made from steel. 
     Deformations of parts of the measuring ram can be determined by means of a measuring sensor, in particular a distance measurement sensor. Preferably, the sensor region of the measuring sensor is oriented towards the first web, which is spaced apart from the contact tongue only by a first gap. During the measurement, the measuring sensor determines the distance between itself and the web surface facing towards it. Such measurements can be carried out with a precision of 0.4 μm and more by means of inductive measuring sensors. 
     Most advantageously, the contact tongue is also connected in one piece with the movable spacer section, and the pressure force exerted thereon during the length measurement is transformed into a longitudinal movement, in particular of the movable spacer section. A movement perpendicular to the longitudinal direction or a rotational movement of the contact tongue does not take place or does not take place to a measurable extent. 
     Most advantageously, for each measuring ram, a first web is spaced apart from the contact tongue via a narrow gap and a second web is spaced apart from the first web by a clearance. In this case, the first web is provided between the contact tongue and the second web. 
     Most advantageously, each of the measuring sensors is connected to the measuring leg in a positionally fixed manner and is passed through said measuring leg through an opening in the respective second web. The sensor surface is arranged essentially free in the clearance between the first and second web. The sensor is oriented towards a surface of the first web remote from the contact tongue. The inductive measuring systems that are preferably used allow highly precise measurements only when the sensor region is essentially free. This means that no components of the measuring ram should be arranged even at the side of the sensor region. This prerequisite for a highly precise measurement is ensured according to the invention by the fact that the sensor head is provided in the clearance between the two webs. 
     In order to determine the overall length of one or more pipe sections, the displaceable measuring leg is connected to a distance meter for measuring the displacement travel, and the distance meter and the at least one measuring sensor are connected to a data processing unit, by means of which the profile length can be determined numerically from the measured data supplied thereto. 
     In one particularly advantageous arrangement of the measuring rams, the latter are provided in two rows next to one another and vertically offset from one another on the displaceable measuring leg. This arrangement of the measuring rams is particularly suitable in conjunction with a holder for the pipe sections that are to be measured simultaneously which is essentially funnel-shaped in cross-section perpendicular to the longitudinal direction of the profiles. 
     So that a variable number of profiles can be measured, the measuring sensors are in each case connected to a switch, by means of which they can be switched on and off individually. As a result, it is also possible to measure simultaneously two, three or just one profile using a measuring device originally designed for example for four profiles to be measured simultaneously. 
    
    
     
       BRIEF DESCRIPTION OF THE VIEW OF THE DRAWINGS 
       The invention will be described with reference to an example of embodiment in six figures. In the figures: 
         FIG. 1  shows a side view of a measuring device according to the invention, 
         FIG. 2  shows a perspective view of a displaceable measuring leg of the measuring device of  FIG. 1 , 
         FIG. 3  shows a cross-sectional view and a plan view along the plane III-III in  FIG. 2 , 
         FIG. 4  shows a perspective view of the measuring leg with pipes to be measured, 
         FIG. 5  shows a perspective view of the measuring leg with four pipe sections to be measured, 
         FIG. 6  shows a schematic view of the position of four or respectively two pipe sections to be measured simultaneously. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the basic arrangement of the measuring device for precisely determining the length of elongate, cylindrical profiles, in particular pipe sections  100 ,  101 ,  102 ,  103 , but also solid profile sections. The measuring device is suitable in particular for use in combination with a pipe cutting or pipe sawing machine (not shown) arranged upstream thereof. 
     Modern pipe cutting machines make it possible to cut pipe sections  1  of a pipe with short cycle times. Less than one second may be necessary for a complete cutting process. During one operating cycle, the pipe is pushed into the sawing machine, cut, and the cut pipe section  1  is removed. The pipe sections  100 ,  101 ,  102 ,  103  that have been cut to size must be produced with extremely high precision. A length predefined by the customer may be allowed to vary for example by no more than 1 μm in order or the pipe section  100 ,  101 ,  102 ,  103  to remain usable. 
     The measuring device according to the invention allows the simultaneous length measurement or checking of a plurality of, in particular one, two, three or four, cut pipe sections  100 ,  101 ,  102 ,  103  simultaneously and with the predefined precision mentioned above. 
     The measuring device comprises a positionally fixed measuring leg  2  and a reaction L. The pipe sections  100 ,  101 ,  102 ,  103  are mounted on a holder  4  between the two measuring legs  2 ,  3  for checking the length. The holder  4  is shaped in such a way that the four pipe sections  100 ,  101 ,  102 ,  103  shown in  FIG. 1  automatically come to rest for each measurement in the same position relative to the two measuring legs  2 ,  3  after they have been placed in the holder  4 . The four pipe sections  100 ,  101 ,  102 ,  103  are in this case arranged parallel to one another in the longitudinal direction. Once the four pipe sections  100 ,  101 ,  102 ,  103  have been positioned in a stable manner and at rest in the holder  4  between the two measuring legs  2 ,  3 , the displaceable measuring leg  3  is displaced towards the pipe section  100 ,  101 ,  102 ,  103  until in each case the two pipe ends  110 ,  111 ,  112 ,  113 ;  120 ,  121 ,  122 ,  123  of the four pipe sections  100 ,  101 ,  102 ,  103  come into contact with a respective one of the two measuring legs  2 ,  3 . During the contact, the length measurement is carried out. The displaceable measuring leg  3  is then moved away from the positionally fixed measuring leg  2  in the longitudinal direction of the pipe sections  100 ,  101 ,  102 ,  103 , and the four pipe sections  100 ,  101 ,  102 ,  103  are removed for delivery or further processing, in particular of the pipe section ends  110 ,  111 ,  112 ,  113 ;  120 ,  121 ,  122 ,  123 . 
     In order to determine the length of each individual pipe section  100 ,  101 ,  102 ,  103 , the measuring leg  3  which can be displaced in the longitudinal direction L has four measuring rams  10 ,  11 ,  12 ,  13  which measure individually. The measuring rams  10 ,  11 ,  12 ,  13  are shown in a perspective plan view in  FIG. 2 . 
     The measuring leg  3  is essentially L-shaped, wherein the lower, shorter leg of the L is provided such that it can be driven in a guide of the measuring device, whereas the long leg of the L protruding upwards next to the holder  4  comprises the four individual measuring rams  10 ,  11 ,  12 ,  13 . The four measuring rams  10 ,  11 ,  12 ,  13  are arranged as two pairs which are located opposite one another and are offset vertically from one another by the spacing of the two measuring rams  10 ,  11  and  12 ,  13 . 
       FIG. 2  shows a contact tongue  15 ,  16 ,  17 ,  18  of each measuring ram  10 ,  11 ,  12 ,  13 , wherein each contact tongue  15 ,  16 ,  17 ,  18  has a bearing surface  15   a ,  16   a ,  17   a ,  18   a  facing towards the holder  4 . The bearing surfaces  15   a ,  16   a ,  17   a ,  18   a  are in each case arranged parallel to a surface formed by an associated pipe section end  6 , while the contact tongues  15 ,  16 ,  17 ,  18  are arranged at a slightly inclined angle relative to the holder  4 . During the length measurement of the four pipe sections  100 ,  101 ,  102 ,  103 , one pipe section end  110 ,  111 ,  112 ,  113  butts against just one respective bearing surface  15   a ,  16   a ,  17   a ,  18   a  of one of the contact tongues  15 ,  16 ,  17 ,  18 . The contact tongues  15 ,  16 ,  17 ,  18  are elastically movable relative to the measuring leg  3 . 
     The cross-sectional view along the plane III-III shown in  FIG. 3  with a plan view of the displaceable measuring leg  3  gives an insight into the interior of the long leg of the L. Here, it is possible to see in each case one of the bearing surfaces of the two left-hand bearing surface pairs  17   a ,  18   a  and of the two right-hand bearing surface pairs  15   a ,  16   a , since the two are in each case arranged precisely one above the other.  FIG. 3  shows the two measuring rams  11 ,  12  arranged next to one another. The two clearances  21 ,  22  assigned in each case to a measuring ram  11 ,  12  and the two gaps  31 ,  41 ,  32 ,  42  assigned in each case to a measuring ram  11 ,  12 , as can be seen in  FIG. 3 , in each case pass completely through the long leg of the L. 
     A comparison with  FIG. 2  shows that the left-hand gaps and the left-hand clearance shown in  FIG. 3  are only approximately half as long as the two right-hand gaps and the right-hand clearance shown in  FIG. 3 . The arrangement shown in  FIG. 3  can particularly advantageously be produced with extremely high precision from a one-piece metal block by means of a wire eroding machine. It is therefore particularly stable and free of wear. 
     Each of the two measuring rams  11 ,  12  shown in  FIG. 3  has in each case just one contact tongue  16 ,  17  with just one associated contact surface  16   a ,  17   a . The contact tongue  16 ,  17  is oriented essentially transversely to the longitudinal direction L and is elastically movable in the longitudinal direction L. An inner end of the contact tongue  16 ,  17  is free, while an opposite, outer end of the contact tongue  16 ,  17  is integrally joined to the solid body of the rest of the measuring ram  11 ,  12 . 
     Each of the measuring rams  11 ,  12  has two parallel webs  51   a ,  51   b ;  52   a ,  52   b  located opposite one another and delimiting the associated clearance  21 ,  22 . A respective first web  51   a ,  52   a  is spaced apart from the associated contact tongue  16 ,  17  via a respective first narrow gap  31 ,  32 . The webs  51   a ,  51   b ,  52   a ,  52   b  run perpendicular to the longitudinal direction L, and they are elastically bendable in the longitudinal direction L. A respective second web  51   b ,  52   b  is provided parallel to the associated first web  51   a ,  52   a  and spaced apart therefrom via a respective clearance  21 ,  22 . Each of the second webs  51   b ,  52   b  has a hole  61 ,  62 , through which in each case one of the measuring sensors  71 ,  72  is passed. Each of the two cylindrical measuring sensors  71 ,  72  is connected in a positionally fixed manner at its end remote from the contact tongue  16 ,  17  to the solid body of the measuring ram  11 ,  12 , while the actual sensor region of the measuring sensor  71 ,  72  is arranged within the associated clearance  21 ,  22  and is at a distance from the web surface remote from the contact tongue  16 ,  17  and is oriented towards said web surface. The sensor  71 ,  72  comprises an inductive measuring system which determines the distance between the sensor surface and the web surface to an accuracy of 0.4 μm. 
     The mode of operation of one of the measuring rams will be described on the basis of the left-hand measuring ram  11  in  FIG. 3 . The two webs  51   a ,  51   b  have in each case a first end and a second end. The first two ends are integrally connected via a spacer section  80  which is positionally fixed relative to the measuring leg, while the two second ends are formed integrally with a spacer section  81  which can move back and forth somewhat in the longitudinal direction. The contact tongue  16  and the movable spacer section  80  rigidly connected thereto are together connected elastically via the two parallel webs  51   a ,  51   b  to the positionally fixed spacer section  80  and thus to the solid body of the measuring leg  3 . 
     When a pressure force of one end  110 ,  111 ,  112 ,  113  of a pipe section  100 ,  101 ,  102 ,  103  presses against the contact surface  16   a  of the left-hand contact tongue  16 , the contact tongue  16  deforms a little into the measuring leg  3 . Due to the integral formation of the entire structure, both the first and the second web  51   a ,  51   b  bend a little into the measuring leg, i.e. in the downward direction in  FIG. 3 . The deformation of the two webs  51   a ,  51   b  is in a certain ratio to the deformation of the contact tongue  16 . The measuring sensor  71  is suitably calibrated and, based on the change in distance between the first web  51   a  and the measuring sensor  61 , can precisely deduce the length of the measured pipe section  100 ,  101 ,  102 ,  103 . The deformation movements of the components are illustrated by arrows. 
     The design of the measuring ram  11  according to the invention, in particular due to the two parallel webs  51   a ,  51   b  arranged perpendicular to the longitudinal direction L, allows the precise guidance both of the contact tongue  16  and of the movable spacer section  81  in the longitudinal direction L. Movements perpendicular to the longitudinal direction L, and also angular or rotational movements, do not take place or do not take place to a measurable extent. 
       FIG. 4  shows the plan view of the displaceable measuring leg  3  as seen in an angled perspective compared to  FIG. 3 . In addition, it is also possible to see in particular three of the four ends  110 ,  111 ,  112 ,  113  of the four pipe sections  100 ,  101 ,  102 ,  103  to be measured. The displaceable measuring leg  3  is not yet in contact with the four pipe section ends  110 ,  111 ,  112 ,  113 . The respective second webs  51   b ,  52   b  in each case have a circular hole  61 ,  62 , through which in each case one of the measuring sensors  71 ,  72  is passed. The measuring sensors  71 ,  72  are cylindrical and are connected fixedly to the measuring leg  3  at their end remote from the pipe.  FIG. 4  clearly shows the one-piece design not just of the four measuring rams  10 ,  11 ,  12 ,  13  but rather also the one-piece design of the L-leg of the measuring leg  3  overall. 
       FIG. 5  shows the positioning of the four pipe sections  100 ,  101 ,  102 ,  103  to be measured on the measuring leg  3 . It can be seen here that in each case just one measuring ram  10 ,  11 ,  12 ,  13  is assigned to each of the ends  110 ,  111 ,  112 ,  113  of the pipe sections  100 ,  101 ,  102 ,  103 , and each pipe section  100 ,  101 ,  102 ,  103  comes into contact with just one of the bearing surfaces  15   a ,  16   a ,  17   a ,  18   a . This ensures that the length of just one of the pipe sections  100 ,  101 ,  102 ,  103  can be measured by each measuring ram  10 ,  11 ,  12 . 
       FIG. 6  shows a diagram of the position of the ends of four or respectively two pipe sections with different cross-sections that are to be measured simultaneously. The four bearing surfaces  15   a ,  16   a ,  17   a ,  18   a  are arranged as two vertically arranged pairs parallel to one another and offset vertically by the spacing of the two pairs. It is thus ensured that, in the case of four pipes to be measured simultaneously, each pipe end comes into contact with just one bearing surface  15   a ,  16   a ,  17   a ,  18   a . In the case of two pipe sections to be measured simultaneously, the uppermost or lowermost measuring sensor of each of the two measuring sensor pairs in  FIG. 6  is switched off and the measurement is carried out only via the two bearing surfaces  16   a ,  17   a  located opposite one another. 
     In addition, it should be noted that the arrangement according to the invention also allows the measurement of the length of just one pipe section. In this case, for example, all four measuring sensors  71 ,  72 ,  73 ,  74  can be switched off and the length measurement then takes place only via the distance meter which is assigned to the displaceable measuring leg  3 . 
     LIST OF REFERENCES 
     
         
           2  measuring leg 
           3  measuring leg 
           10  measuring ram 
           11  measuring ram 
           12  measuring ram 
           13  measuring ram 
           15  contact tongue 
           15   a  bearing surface 
           16  contact tongue 
           16   a  bearing surface 
           17  contact tongue 
           17   a  bearing surface 
           18  contact tongue 
           18   a  bearing surface 
           21  clearance 
           22  clearance 
           31  gap 
           32  gap 
           41  gap 
           42  gap 
           51   a  web 
           51   b  web 
           52   a  web 
           52   b  web 
           61  hole 
           62  hole 
           70  sensor 
           71  sensor 
           72  sensor 
           73  sensor 
           80  spacer section 
           81  spacer section 
           82  spacer section 
           100  profile 
           101  profile 
           102  profile 
           103  profile 
           110  profile end 
           111  profile end
         112  profile end   
     
           113  profile end 
           120  profile end 
           121  profile end 
           122  profile end 
           123  profile end 
         L longitudinal direction