Abstract:
A guide with a measuring device has a guide base with a longitudinal axis, a runner guided on the guide base in a direction of the longitudinal axis, a measuring device which measures a position of the runner in the direction of the longitudinal axis of the guide base or a condition of the guide base and having a measuring head arranged on the runner and connectable with an evaluating circuit for sensing the measuring guide, and an adapter plate arranged between the measuring head and the runner.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a guide with a measuring device, as well as to a method of producing such a guide. 
   More particularly, the present invention relates to a guide with a measuring device, which includes a guide base with a longitudinal axis, a runner guided on the guide base in direction of the longitudinal axis, a position measuring device which measures the position of the runner in direction of the longitudinal axis of the guide base, and a measurement standard arranged on the guide base. 
   Such a linear guide with the measuring device is disclosed for example in the brochure RD 82 350/11.98 “STAR-ball and Roller Rail Guides with Integrated Measuring System” of the Company Rexroth Star GmbH (FIG.  2 ). The known linear guide with the integrated measuring system  10  is composed of a guiding rail  12  with a longitudinal axis A, on which a runner is supported longitudinally movable over not shown roller bearings. 
   The measuring system  20  is formed by a separate sensing element (measuring head)  22  and a measuring standard  24  integrated in the guiding rail. The measuring head mounted directly on the runner contains the sensing system and electronic system for the signal conditioning. The measuring standard, a steel partition with a high precision structure, is arranged in a groove of the guiding rail and protected by a stainless, tightly welded high-grade steel band. 
   The known linear guide with integrated measuring system has the disadvantage that due to the direct application of the measuring head on the runner, angular deviations due to tolerances can occur, which negatively influence the measuring results. Moreover, in the known system a high expenses for the adjustment of the sensor arranged in the measuring head take place. 
   In accordance with a second aspect, the present invention deals with a guide with a measuring device which includes a guide base with a longitudinal axis, a runner guided on the guide base in direction of the longitudinal axis, and a measuring device which measures the condition of the guide base with a measuring head arranged on the runner and connected with an evaluating device. 
   SUMMARY OF THE INVENTION 
   Accordingly, the objective of the invention is to provide a guide with the measuring device, which makes possible a simple and position-accurate mounting of the measuring head. 
   In accordance with the present invention, this objective is achieved in that an adapter plate is arranged between the measuring head and the runner. 
   With the adapter plate, and position-accurate positioning of the measuring head is guaranteed, which then guarantees a predetermined distance of the sensor to the guiding base when the measuring head is exchanged. Moreover, there is a possibility to support the runner and the measuring head separately, so that when necessary they can be assembled in a correct position without expensive adjustment steps. 
   The inventive guide includes a guide base and a runner which is longitudinally displaceably supported on the guide base in direction of its longitudinal axis. The guide can be formed as a linear or curved guide such as a sliding guide, a rolling guide, a fluid guide or a magnetic guide. 
   The guide base can be rectilinear or curved in form of a shaft, a spline shaft or a profile rail. A measuring standard is arranged on the guide base. Preferably, the measuring standard is arranged in a groove of the guide base and protected by a cover band from outer influences. It is however recommended to arrange the measuring standard outside on the guide base. Depending on the type of the guide, the runner can be formed as a sliding block, a carriage or a guiding car. On an end side of the runner which extends substantially orthogonal to the longitudinal axis of the guide base, an adapter plate is mounted. The measuring head is fixed on the adapter plate. 
   The measuring head is formed as a separate housing, in which at least one sensor is received. The sensor can be a directional sensor. In accordance with the second aspect of the invention, the sensor is a sensor for determination of the condition of the guide base, in particular for determination of the availability of a lubricant on the guide base. 
   Seals and cover arranged on the housing close the housing tightly, so that the measuring head can be formed as an assembly protected from outer influences, such as from dirt or cooling fluid. 
   The adapter plate has a positioning means, which correspond to the positioning counter means on the housing. The positioning means can be formed on the adapter plate as openings, and the positioning counter means on the housing can be formed as pins. It is also possible to form the positioning means on the adapter plate and the housing as openings, in which separate pins are introduced. 
   The positioning means on the adapter plate can be formed as elongated openings. Thereby a subsequent adjustment of the housing in a plane extending orthogonal to the longitudinal axis of the guide base is possible. 
   The adapter plate and the housing can be connected with one another by screws. For this purpose in both components corresponding mounting receptacles are provided, in which mounting means and mounting counter means can be received. 
   It is advantageous when the positioning-and mounting means are available in one of the components, the adapter plate of the housing, so that the positioning and mounting are simplified. 
   The inventive method for producing such a guide with a measuring device includes the steps of:
         Mounting the adapter plate on the runner and placement of the runner on the guide base or on an auxiliary device, or vice versa;   plane treatment of the surface of the adapter plate extending orthogonal to the longitudinal axis of the guide base and facing away from the runner;   insertion of the positioning means into the plane-treated surface of the adapter plate, and mounting the measuring head on the adapter plate.       

   In accordance with this method, the runner is located on the guide base or on an auxiliary device. The adapter plate before or after the placement of the runner on the guide base or the auxiliary device, can be mounted by screws on the runner. 
   When the runner is located on the guide base or the auxiliary device and the adapter plate is located on the runner, a plane treatment of the surface of the adapter plate which extends orthogonal to the longitudinal axis of the guide base and faces away from the runner is performed. With this plane treatment, a plane milling can be used. 
   After the plane treatment, positioning means can be introduced in the plane-treated surface of the adapter plate. Advantageously, they are formed as openings or longitudinal openings. 
   Furthermore, the housing is provided with positioning counter means, which can be connected of one piece with the housing or can be formed as pins introduced in the housing, so that the housing can be plugged directly on the adapter plate. 
   In case when the positioning means of the adapter plate are formed as elongated holes, an additional adjustment of the measuring head is possible, and in particular in a plane which extends orthogonal to the longitudinal axis of the guide base. For this purpose in a first step a reference part, for example a ball or a pin, can be introduced in a longitudinal opening of the adapter plate. Subsequently the plugging of the housing is performed. With a mounting means screwable preferably orthogonal to the longitudinal axis of the guide base, a positioning counter means of the housing is pressed on the reference part. In this condition a measurement of the position of the measuring head relative to the guide base is performed. When a correction of this position is needed, the reference part is exchanged by a part with required dimensions. 
   In the last step the mounting of the measuring head and the adapter plate is performed by means of the mounting means and counter mounting means provided for this purpose. 
   The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view schematically showing a guide with a measuring device in accordance with the present invention. 
       FIG. 2  is Prior Art. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a linear guide in accordance with the present invention which is identified as a whole with reference numeral  10 . The linear guide  10  is a ball-rail guide with a guide rail  12  and a guide car  14 , on which a measuring head  22  is mounted. 
   The guide rail  12  has a longitudinal axis A. Running tracks  16  for not shown balls are provided on both side surfaces of the rail extending in a longitudinal direction. A measuring standard  24  is arranged in the rail side surface between the ball running tracks  16  and extends over the total axial length of the rail  12 . The measuring standard  24  is tightly welded by a cover band. 
   The guide carriage  14  is composed of a substantially U-shaped main body and two end plates which are mounted on its end sides by screws  18 . Supporting running tracks for the balls are made in the main body and correspond to the rail-side running tracks  16 . In the main body, ball return tracks are arranged and formed as openings, which together with the supporting running tracks and the deviating tracks located in the end plates provide an enclosed ball circulation. 
   An adapter plate  30  is mounted on an end plate of the car  14 . In this embodiment the mounting screws  18  of the end plate have a screw head with an inner thread, in which mounting screws  32  of the adapter plate  30  can be screwed. For providing centering of the adapter plate  30 , the mounting screws  13  are provided with a centering head which in the screwed condition extends axially over the end plate, in order to assemble with a corresponding centering recess in the adapter plate  30 . 
   Moreover receiving openings  34  are provided in the adapter plate  30 , as well as transverse openings  36 , and positioning openings  38 . 
   While the openings  34  and  36  are provided for receiving the mounting means, such as anchors  42  or threaded pins  44 , the positioning openings  38  serve for receiving of positioning counter means, such as pins  40 . 
   The positioning openings  38  can be also formed as elongated holes  38 ′ which are shown by a broken line in the drawing. 
   The measuring head  22  is composed substantially of a housing  28 , in which a sensing system and an electronic system are accommodated. Various seals and covers can close the housing  20  to form a tight assembly protected from outer influences. Openings for the pins  40  and the anchors  42  are provided on the housing  26 . 
   The method for producing an inventive linear guide with a measuring device will be described hereinbelow. 
   Both the linear guide with the guiding rail  12  and the guiding car  14  as well as the measuring head  22  are completely prefabricated components, such as for example located on the bearing. There is the advantage that on the measuring head  22 , the pins  40  and the anchors  42  are already arranged. 
   The adapter plate  30 , which can be composed of an aluminum alloy, has up to the positioning openings  38 , all openings required for mounting of the end plate and for receiving the measuring head  22 . Also, the adapter plate  30  can be formed as a prefabricated assembly located on the bearing. 
   The guide car  14  is placed on the guide rail  12 . Before or after the placement of the car  14 , the adapter plate  30  is mounted by screws  32  on the car  14 . 
   On the thusly mounted linear guide, a plane milling of the adapter plate  30  is performed, so that the plane-treated surface forms a plane extending exactly orthogonal to the longitudinal axis A of the guide rail  12 . 
   Then the complete measuring head  22  is mounted on the adapter plate  30 , in that the pins  14  and the anchors  42  are introduced into the positioning opening  38  or the receiving openings  34  provided for measurement. BY turning of the threaded pins  40  into the transverse opening  38 , finally a position-accurate mounting of the measuring head  22  on the adapter head  30  is performed. 
   In the case when it is desired to provide a post adjustment, in the adapter plate  30  instead of the positioning openings  38 , elongated openings  38 ′ are arranged. In these longitudinal openings, the pins  40  mounted on the measuring head can be displaced by a not shown adjustment means. Instead of the positioning openings  38 , elongated holes  38 ′ can be arranged, in which the pins  40  mounted on the measuring head can be displaced by means of a not shown adjusting means. For this purpose in a first step a reference ball with known dimensions is inserted in an elongated hole  38 ′, on which a pin  40  is pressed. After the determination of the position of the measuring head  22  with respect to the guide rail  12 , the measuring head  22  is screwed with the adapter plate  30 . If the desired position of the measuring head  20  can be not be obtained, the reference ball is exchanged. 
   It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions and methods differing from the types described above. 
   While the invention has been illustrated and described as embodied in guide for measuring device, and method with producing such a guide, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.