Boring or penetrating the earth – With means to feed drive
Reexamination Certificate
1998-06-16
2001-07-31
Tsay, Frank (Department: 3672)
Boring or penetrating the earth
With means to feed drive
C175S113000, C173S148000
Reexamination Certificate
active
06267187
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to apparatus for producing and expanding earth boreholes and for destroying and replacing underground pipelines or for driving in pipes.
BACKGROUND AND PRIOR ART
Apparatus of this kind is known and has often proved its worth in practice. However, it requires a considerable amount of space and, for example in the case of horizontal boring, needs a correspondingly large excavation or launch pit.
A boring apparatus for destructive replacement of an underground pipeline is known, for example, from U.S. Pat. No. 4,507,019. This apparatus comprises a frame with an adjustable mounting for two feed cylinders connected to a sliding carriage. Mounted on the carriage is a rotary drive of which the horizontal shaft is provided with an external screw thread and can be screwed on to the internal screw thread at the rearward end of a drill string made up of a number of sections. As a result of the length of the frame the known apparatus requires a large excavation or launch pit.
Added to this is the fact that when lengthening the drill string the new section of the string has to be aligned with the external thread of the drive shaft and also with the internal thread at the rearward end of the drill string or of the last section thereof, and then screwed first of all on to the external thread of the drive shaft and then into the internal thread of the drill string. This requires a double screwing operation for each section of the string and therefore is not only unnecessarily time-consuming but also increases the space required, since the distance between the drive shaft on the one hand and the rearward end of the drill string on the other hand must be greater than the length of a string section.
A further disadvantage of the known boring apparatus is that before the addition of a new section to the string the drive shaft must be unscrewed from the internal thread at the end of the drill string while the drill string is held fast by means of expensive auxiliary units to enable the screw thread of the drive shaft to be unscrewed from the end of the drill string. For this purpose German Offenlegungsschrift 41 13 422 proposes an undercarriage head provided with a clamping device and with a clamping and rotating device. The clamping device has two clamping cheeks which embrace the pipe and are driven by hydraulic cylinders in order to grip the pipe fast between them and prevent it from rotating. The clamping and rotating device includes a carrier which can rotate about the axis of the pipe on which are fitted two clamping cheeks which act on the pipe and are driven by respective cylinders. A further cylinder drives a holder so as to cause it to rotate round the axis of the pipe.
The above-mentioned disadvantages are also suffered by a boring apparatus known from German patent 41 22 350, which needs so much space that it is mounted above ground and first creates a downwardly inclined pilot bore in order to reach the laying depth and then continues boring horizontally. However, such apparatus is not suitable for laying house connections, since on account of its large external dimensions it cannot be accommodated in the sidewalk region. Furthermore it is not possible even to reach the laying depth in the sidewalk region in order to connect the house connection to a main line laid along the street.
OBJECT OF THE INVENTION
Starting from this state of the art, the object of the invention is to provide an apparatus which requires little space and which permits rapid connection of a string section on the one hand to the rotary drive and on the other hand to the rearward end of a string which is already present underground.
SUMMARY OF THE INVENTION
To this end, in accordance with the invention in an apparatus of the above-mentioned kind the rotary drive is provided with a plug-in coupling comprising a chuck on the one hand and a locking portion at the end of a string or string section which can be inserted into the chuck in a simple manner without the need for screwing up. This can for example be done through a radial opening in the chuck.
The chuck avoids the need for a screw on the drive side and can include a cup pointing in the direction of the axis of rotation and open in the direction of advance, into which the rearward end of the new string section can be pushed. This cup then prevents the string section from falling out through the insertion opening during rotation. If the string section or the cup is provided with a seal it is possible for the string to be supplied with a liquid through a supply line ending in the base of the cup.
The plug-in connection can be formed in the manner of a bayonet joint and, for example, include an end collar behind which is located at least one radial stop which on rotation of the chuck connected to the drive shaft of the rotary drive in both directions acts as a driver to screw the front end of the new string section to the rearward end of a string which is already present underground. This driver preferably cooperates with a stop face in the string section.
The feed drive and the rotary drive with the plug connection are preferably mounted in a frame having a string guide, in which at least one thrust cylinder can be mounted in order to move the rotary drive with the plug connection forward by about the length of one string section. This can also be done by means of a third thrust cylinder, preferably mounted in the middle between the first and second thrust cylinders, the piston rod of which is then connected to the rotary drive. In this way a short overall length is obtained with high thrust force and relatively great string section length. Telescopic cylinders are also suitable as thrust means.
However, it is a disadvantage of such cylinders that the forces in the respective stages are different and so do not deliver continuous feed and traction forces or a continuous feed rate. To lengthen the feed path, the transfer of force from the cylinder to the rotary drive can also take place through a chain routed as in a differential pulley, thereby for example enabling the feed path to be doubled.
Instead of three separate cylinders, it is also possible to employ a cylinder block which is provided with three piston rods, one of them advancing in one direction and the other two in the opposite direction.
To provide for rapid screwing of the front end of a string section on to the rearward end of the drill string, the frame can be provided with a radially movable holding claw, which engages with at least one key face at the rearward end of the string and serves to prevent rotation during screwing up. The holding claw is preferably articulated to one end of a two-armed lever having a pivot fixed relative to the frame, which makes linear movement of the claw possible for example when the pivot pin reaches through a slot in the claw carrier.
In order to fix the apparatus in the excavation or launch pit the frame can be provided with horizontally extendable support braces through which the recoil forces can be led into the ground.
The string comprises several sections each having an internal screw thread at one end and a locking portion with an external screw thread at the other end. It is suitable not only for apparatus of the aforementioned kind but also, in combination with the complementary chuck, for other apparatus having a feed drive and optionally also a rotary drive, for example for rod and pipe extrusion apparatus.
The locking portion is preferably provided with at least one key face for non-rotatably fixing the string section as the next following string section is screwed on. The locking portion can further include a stop face, and a tubular filler body of a material of relatively low specific gravity, for example of plastics material, may be located in the interior of the string section. This filler body serves to reduce the cross-section of the opening of a tubular drill string to the appropriate size for passage of a flushing, cutting, lubricating or steering liquid, and in view of its relatively low specific gra
Balve Gerhard
Puttmann Franz-Josef
Merchant & Gould P.C.
Tracto-Technik - Paul Schmidt - Spezialmaschinen
Tsay Frank
LandOfFree
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