Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Advancing subterranean length of pipe or cable
Reexamination Certificate
1999-03-30
2001-05-29
Pezzuto, Robert E. (Department: 3673)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Advancing subterranean length of pipe or cable
Reexamination Certificate
active
06238141
ABSTRACT:
The invention relates to an apparatus for the static making or widening of microtunnels and/or the destruction of old pipework, in which a push-pull drive engages via coupling means on projections or in recesses of a linkage having a tool at the end.
A drilling apparatus of this type is disclosed in German Published Application 196 08 980. It consists of a mounting having a hydraulic piston/cylinder unit which moves a carriage linearly and reciprocally. The carriage is connected to a pawl which, when the carriage is advanced, engages behind a rung of the ladder-type linkage and thus moves the ladder-type linkage with the drilling head forwards in the drilling direction in accordance with the stroke of the hydraulic piston/cylinder unit. At the end of the stroke the pawl is automatically released from the rung and the carriage moves back into its starting position. During this, the ladder-type linkage is not fixed and, accordingly, generally recoils to a greater or lesser extent under the action of the -earth on the drilling head at the front end of the ladder-type linkage. In this way, the advance of the linkage is shortened, at every stroke, to a greater or lesser extent depending on the composition of the earth. Since this happens after each stroke, and since a great many strokes are necessary when drilling over longer distances, the recoil inevitably leads to a substantial loss of performance. An additional effect of the recoil is that the pawl and the ladder-type linkage are no longer in the reciprocal position which guarantees that the pawl engages between two rungs of the ladder-type linkage. In this event, the linkage and/or the pawl have to be pushed towards one another until the pawl is located precisely above the intervening space between two ladder rungs.
This loss of performance is not only noticeable when the apparatus is being used for drilling, but also when, for example at the end of a pilot drilling operation, the drilling head is replaced by a widening or clearing head and this is drawn back through the pilot drilling to the launch pit because in the case of widening, too, the .earth exerts an action on the pulling linkage counter to the direction of movement of the widening or clearing head and moves the former a greater or lesser distance back when the carriage moves back to its starting position.
The object of the invention is thus to avoid the loss of performance resulting from the abovementioned recoil of the linkage when drilling a hole with a clearing head and/or when widening a pilot drilling or, alternatively, when destroying and replacing ground-laid pipework with the aid of a tool.
The object is achieved by means of the independent claims. Advantageous embodiments will be found in the subclaims.
In detail, the object is achieved in that the apparatus is provided, according to the invention, with at least one linkage locking system which fixes the linkage in the position of advance achieved after each stroke, when the coupling means is released from the linkage.
The linkage locking system consists preferably of two mutually opposing retaining jaws or of a locking pawl which is lowered automatically after passing over a linkage rung and engages behind the rung, until the rung moves on in the direction of advance during the next stroke.
The locking pawl can be so arranged that it can be pivoted through approximately 180° and, accordingly, exerts its locking action in both directions of the ladder-type linkage. This is readily possible if the locking pawl possesses, for example, two stopping faces arranged at an angle with respect to each other between which a stopping lug extends by means of which the locking pawl is supported in one or the other direction on a ladder rung.
The apparatus is provided, in a further preferred embodiment, with at least one dragging pawl, for example a stationary locking pawl, and a thrust pawl which is moveable in the longitudinal direction of the linkage and is connected to the push-and-pull drive with, in each case, two directions of action.
These pawls also can, for example, be arranged on a pivot pin in such a manner that they can be pivoted through approximately 180° and, accordingly, exert their action in both directions of the linkage. This is readily possible if, for example, the pawls possess one or even two stopping faces arranged at an angle to one another with which they can be brought into a non-positive or positive active connection with the linkage in one direction or the other.
In this manner, it is possible to move the linkage forwards stepwise in push or pull operation, with the aid of the thrust pawl, and to fix it after each movement step, with the aid of the stationary locking pawl, until the linear drive with the thrust pawl has returned to its starting position and the thrust pawl again comes into active connection with the linkage.
In order to allow this, the pawls may be so contoured that they each possess at least one sliding surface. The sliding surface makes it possible for the thrust pawl, during the backward movement of the linear drive, to be slid or dragged loosely over the linkage, for example over the rungs of a ladder-type linkage, until, at the beginning of the advancing movement, it again comes into active connection or engagement with the linkage. On the other hand, during the advancing movement of the linkage, the locking pawl slides by means of its sliding surface over the linkage until, at the end of the advancing movement of the linkage, it again comes into active connection or engagement with the linkage and temporarily locks the linkage. Here again, a type of dragging movement takes place.
The locking pawl and, optionally, the thrust pawl also should be capable of being locked in a neutral position in order to enable the linkage to be displaced reciprocally without obstruction.
In pull operation, for example if a widening or clearing head is to be pulled through a pilot drilling or a trolley provided with cutting discs or a bursting head is to be drawn through ground-laid pipework in order to destroy ground-laid pipework, in order to slit the walls of the pipe in the longitudinal direction, the two pawls merely need to be pivoted by hand or automatically through approximately 180° in order to come into active connection or engagement with the linkage in alternation, in the manner already described in connection with push operation,
The locking pawl is preferably fixed to the apparatus, and the thrust pawl is preferably arranged on a moveable carriage connected to a linear drive. A double-action hydraulic cylinder may serve as a linear drive. In this case, the two cylinder spaces can be connected via one hydraulic line each, having a ¾-way valve, to a pressure source; between the hydraulic lines a shuttle valve is connected, having a manometer which measures the current pressure in each case and, when the maximum pressure is achieved, switches the ¾-way valve by means of a control unit and so connects one or the other hydraulic line to the pressure source.
This permits automatic operation of the advancing trolley, so that manual work is now required only for the insertion and coupling of the linkage sections. In addition, damage can be avoided if the apparatus is set to maximum insertion and/or pulling pressure, so that the apparatus is automatically switched off if it meets an unexpected obstacle in the soil.
If the apparatus according to the invention is used to draw a cutting trolley and, at a distance behind it, a widening or clearing head also through ground-laid pipework, in order first to slit the pipework open in the longitudinal direction and then to widen it with the aid of the widening or clearing head, together with the surrounding earth, and at the same time to draw a new pipe into the earth with the aid of the widening head, then a high flexural stress may be imposed on the linkage connection between the cutting trolley and the widening head.
The invention provides a remedy here in the form of an articulated connection of the linkage, for example cons
Kaufmann Bernhard
Prutti Frank
Puttmann Franz-Josef
Riekes Andreas
Merchant & Gould P.C.
Pechhold Alexandra K.
Pezzuto Robert E.
Tracto-Technik-Paul Schmidt Spezialmaschinen
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