Abstract:
The invention relates to a drilling apparatus and a method for introducing a drilling element into the soil. The drilling element is rotatably and slidably supported on a mast, with a torque being applied through a rotary drive located on the mast. In order to support the torque an additional turning device is fixed to the mast, which can be engaged with the driven drilling element.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a drilling apparatus for introducing a drilling element into the soil comprising a rotary drive, which is supported on a mast for introducing the drilling element arranged rotatably and slidably on the mast, and a turning device having a collet that can be turned by means of at least one operating cylinder. 
   The invention further relates to a method for introducing a drilling element into the soil, wherein the drilling element is set into rotation by means of a rotary drive and slid along a mast. 
   2. Description of Related Art 
   In the prior art a variety of soil drilling machines is known which are especially employed in specialist foundation engineering for foundation measures. With these drilling machines a drill hole can either be produced by means of a drilling tool, with the hole being then filled with concrete for example in order to produce a foundation pile. Furthermore, with a drilling apparatus a screw anchor or a bored pile with a screw tip can also be screwed directly into the soil. Especially in the latter case relatively high torques may be required for great pile lengths in order to screw the pile into the soil. 
   The drive of the drilling apparatus is to be designed according to the maximum torque to be expected, for which reason the drive constitutes a major cost factor in a drilling apparatus. 
   To produce cased drillings, drilling apparatuses are known which are additionally provided with a casing machine that serves to screw in the supporting casings. Such casing machines have a collet which can be turned through operating cylinders. 
   SUMMARY OF THE INVENTION 
   The invention is based on the object to provide a drilling apparatus, with which even drilling operations requiring a particularly great amount of power can be carried out with a construction that is as simple and cost-effective as possible. Furthermore, it is an object of the invention to provide an efficient method for introducing a drilling element into the soil. 
   The drilling apparatus according to the invention is characterized in that the turning device is fixed to the mast and can be engaged with the drilling element driven by the rotary drive in order to support the torque. 
   A basic idea of the invention resides in the fact that a turning device is provided directly on the mast, with the turning device being directly engageable with the drilling element, whereby at least at specific points of time an additional torque can be applied to the drilling element besides the normal rotary drive. The drilling element can either be a drilling tool, which is extracted again from the drill hole after the introduction, or a screw pile or anchor element which directly serves as a foundation element and remains in the soil. If the torque of the rotary drive does not suffice to introduce the drilling element, a torque support can be effected by means of the turning device. By using a collet with an operating cylinder to turn the collet it is possible to generate a very high torque for a limited turning angle. As experience has shown that during drilling the maximum drilling torque is not present during the entire drilling time but only as a peak load at very limited points of time, the drive of the drilling apparatus can be laid out in a cost-effective manner for the normal drilling torque. To bridge the torque peak the torque support can be employed. 
   According to the invention it is preferred that the turning device is fixed to the lower end portion of the mast. This permits a torque support even when the drilling element is almost completely inserted into the soil. 
   An efficient drilling operation is achieved in accordance with the invention in that the turning device is supported on the mast by a supporting bearing, through which the collet can be pivoted and/or turned. As a result, the torque support can act on the drilling element even during a feed motion of said drilling element. 
   A particularly tension-free arrangement is achieved according to the invention in that the at least one operating cylinder and/or a supporting arm of the collet is mounted on gimbals through the supporting bearing. As a result, certain deviations of the drilling element can also be compensated flexibly by the supporting bearing so that a very good torque transmission by the turning device is achieved at all times. 
   Another embodiment of the invention is characterized in that the collet has two clamping jaws which can be adjusted by means of a clamping cylinder between a clamping position and a free-running position. An adjustable collet permits a clamping of the drilling element along the entire length and is also able to compensate for differences in diameter of the drilling element. The clamping jaws can be adapted to fit the respective drilling element so that a good transmission of force is ensured in the clamping position and a distance to the drilling element is maintained in the free-running position. The clamping cylinder and the operating cylinders of the turning device are preferably designed as hydraulic cylinders which are able to generate particularly high forces. 
   In principle, the feeding of the drilling element can be applied by the rotary drive alone through corresponding screw threads located on the drilling element. The feeding can take place for example through a rope winch or a toothed rack. In addition, the mast can be designed as a leader, with an upper part of the mast being movable with respect to a basic mast. 
   Finally, it is intended according to the invention that a control device is provided, through which the rotary drive, the feed drive and the turning device can be operated in a coordinated manner. The control device can thereby coordinate the continuous rotary drive with the discontinuous turning device. Thus, during the periods of the torque support by the turning device the rotary drive can also be operated in a discontinuous manner. 
   For a high flexibility of the drilling apparatus it is intended according to the invention that the mast is pivotally supported on a carriage. In this way the mast can be pivoted together with the turning device between an approximately vertical operating position and an approximately horizontal transport position. 
   The method in accordance with the invention is characterized in that a turning device having a collet is engaged with the drilling element and in that a supportive torque is applied to the drilling element through the turning device by means of at least one operating cylinder. This way the turning device can balance out the torque peaks so that the continuous rotary drive can be laid out in a cost-effective manner for the normal torque load. 
   For an efficient drilling progress it is intended according to the invention that the turning device is pivoted and/or moved at least gradually with the drilling element in the drilling direction. To this end the turning device is movably arranged through a corresponding pivot or slide bearing on the mast between an upper and a lower position. By preference, a resetting device is provided through which the turning device is reset from the lower position to the upper position again. In the upper position the turning device can then be moved to the lower position again in response to the feeding through a corresponding clamping with the drilling element. 
   To coordinate or synchronize the discontinuous and continuous drives, it is intended according to the invention that the rotation of the rotary drive, the feed motion of the drilling element and the operation of the turning device are controlled in a coordinated manner. 
   Furthermore, it is intended in accordance with the invention that the torque support is effected at specific periods of time only, in particular during a final drilling phase. When a drilling element is drilled into the soil the torque load increases with an increasing drilling depth due to the higher friction surfaces. Therefore the torque support is preferably effected in the final phase so that a reliable turning motion is ensured at this point of time, too. 
   Generally, the drilling element can be constituted by a drilling tool that can be removed from the drill hole again, such as a drilling screw, a drilling bucket or any other chosen drilling tool that operates in a continuous or discontinuous fashion. However, it is preferred according to the invention that a screw pile, in particular having a tapered screw tip, is used as drilling element. Especially during the drilling-in of such foundation piles with screw flights high torques usually have to be applied, since a considerable part of the soil is being displaced whereby a high surface friction is generated. 
   Another embodiment of the invention resides in the fact that in order to take foundation measures the screw pile is driven through loose soil layers up to a solid soil layer, with the torque support being effected for the introduction into the solid soil layer. Thus, with the rotary drive screw piles can be screwed through the loose soil and anchored efficiently in the solid soil layers with the support of the casing device. 

   
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the following the invention will be described by way of a preferred embodiment which is schematically shown in the accompanying drawings. In the drawings: 
       FIG. 1  shows a side view of a drilling apparatus according to the invention; 
       FIG. 2  shows a schematic side view of the turning device; 
       FIG. 3  shows a top view onto the turning device of  FIG. 2  and 
       FIG. 4  shows top views onto the turning device in various turning positions. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The drilling apparatus  10  according to the invention shown in  FIG. 1  has a carriage  20  designed as a crawler, to which a mast  14  is pivotally hinged between a horizontal transport position and a depicted vertical operating position. The mast  14 , which can be pivoted in a known manner by hydraulic cylinders, is constructed as a so-called leader with a stationary basic mast  16  on which a movable mast  15  is slidably supported through a moving device. 
   On the movable mast  15  a rotary drive  12  is slidably supported through a feed drive  26 , which rotary drive serves to drive a drilling element not depicted here. To the lower end of the mast  14  a turning device  30  is fixed as a torque support which shall be explained in more detail hereinafter. A control device  70  is provided to operate the rotary drive  12 , the feed drive  26 , and the turning device  30 . The connection of the control device to the rotary drive  12 , the feed drive  26  and the turning device  30  is shown by phantom lines. 
   In  FIG. 3  the turning device  30  is shown with a collet  32  which encloses a drilling element  50 . The collet  32  illustrated in  FIG. 3  is in the free-running position in which the collet is spaced on all sides from the enclosed drilling element  50  so that the drilling element  50  can be moved freely by the collet  32  in the drilling direction that extends perpendicularly to the plane of the drawing. 
   The collet  32  comprises an arched collet base  31 , at both ends of which a clamping jaw  33 ,  34  is each pivotally hinged. The free ends of both clamping jaws  33 ,  34  are arranged opposite each other and connected by means of a clamping cylinder  46 . By retracting the clamping cylinder  46  the clamping jaws  33 ,  34  can be moved towards each other, whereby a force-locking connection can be established with the drilling element  50 . 
   The collet base  31  is fixed to the mast  14  via a length-adjustable supporting arm  38  by means of a supporting bearing  40 . For a Cardanic suspension the supporting bearing  40  has a horizontal swivel bolt  42  that is rotatably supported in a bearing block  45 . On the horizontal swivel bolt  42  a vertically directed vertical swivel bolt  44  is provided, on which the mast-facing end of the supporting arm  38  and the mast-facing ends of two operating cylinders  35 ,  36  are pivotally supported. The operating cylinders  35 ,  36  serve to turn the collet  32  with respect to the supporting bearing  40 , with the collet-facing ends of the operating cylinders  35 ,  36  being each pivotally supported on the collet base  31  in those points in which the clamping jaws  33 ,  34  are also supported on the collet base  31 . 
   The supporting bearing  40  renders it possible that the collet  32  can follow the clamped drilling element  50  when this is moved in the drilling direction, as is schematically shown in  FIG. 2 . When a feed motion of the drilling element  50  takes place during a drilling operation, the collet  32 , being in the clamping position, follows with its operating cylinders  35 ,  36  the motion of the drilling element  50  towards the ground. After the clamping cylinder  46  has been opened, the collet  32  has to be reset upwards for a renewed turning operation, which is possible by means of a resetting device  60 . 
   The depicted resetting device  60  includes a pressure plate  62  supported on the horizontal swivel bolt  42 , which plate can be reset by means of a compression spring  66  that rests on an abutment  64 . 
   The operation of the torque support of the turning device  30  is schematically shown in  FIGS. 4   a  to  4   c .  FIG. 4   b  shows the free-running position which has already been described in conjunction with  FIG. 3 . 
   According to  FIG. 4   a  the clamping cylinder  46  is retracted, with the clamping jaws  33 ,  34  enclosing the drilling element  50  in a force-locking manner. By retracting the first operating cylinder  35  and extending the second operating cylinder  36  an anticlockwise turning of the collet  32  and thus of the clamped drilling element  50  can be effected. This turning can be used to support the torque. 
   According to  FIG. 4   c  a clockwise turning of the collet can be achieved on the other hand by extending the first operating cylinder  35  and retracting the second operating cylinder  36 .