Tool driving or impacting – Impacting devices – Selective axial direction of impact
Patent
1997-01-27
1998-12-22
Smith, Scott A.
Tool driving or impacting
Impacting devices
Selective axial direction of impact
173 18, 173211, 175299, B25D 900, B25D 1100, E21B 100
Patent
active
058508848
DESCRIPTION:
BRIEF SUMMARY
This invention relates to moling apparatus.
Moling apparatus, is used for making holes in the ground, driving pipes into the ground, driving explosives into the ground for mining or military engineering, and for driving coring tubes into the ground to take core samples.
Of the above-mentioned uses of such apparatus, making holes in the ground for pipes, cables and ducts, is an increasingly important area of use for such apparatus because of the advantages such trenchless laying techniques have over the traditional open trench method. Not only are trenchless methods much less labour intensive, they are also less harmful to the environment.
However despite the apparent advantages of such apparatus over open trench methods, existing moling devices are not utilised as extensively as they could be. This is because existing machines tend to be unreliable, difficult to steer accurately without expensive guidance systems, inefficient, and unable to respond to differing ground conditions as the nature of the ground penetrated by the device changes.
U.S. Pat. No. 5,031,706 discloses a self-propelled pneumopercussive ground penetrating machine which addresses some of the above-mentioned problems in an attempt to produce a machine having a decreased energy consumption and increased velocity. The machine includes a hollow cylindrical housing, having a pointed head section, a striker which reciprocates inside the housing and an air distribution mechanism. The machine operates by accelerating the striker by compressed air to cause it to impact the front end of the housing. As a result of the impact the machine penetrates the soil a certain distance. The striker then travels backwards and is braked. This cycle is then repeated. U.S. Pat. No. 5,031,706 is particularly concerned with a valve operated air distribution mechanism which is claimed to increase the efficiency of the machine compared with earlier designs of pneumopercussive machines. The machine includes means for informing an operator of the rate of progress of the machine through the ground so that the operator can tell if the machine hits an obstacle, such as a rock and the operator can put the machine into reverse mode and attempt to steer round the rock. However despite the apparent improvements over existing moling devices the machine disclosed in U.S. Pat. No. 5,031,706 is complicated in design and would appear to be expensive to manufacture due to its complicated design. Further although an increase in efficiency is apparently achieved over existing moling devices, U.S. Pat. No. 5,031,706 does not properly address the problems of steering and response to ground conditions. Finally a less complicated machine could show improvements not only in the cost of the machine itself but also in reliability.
U.S. Pat. No. 3,741,315 provides a device for drilling ground in which the cutting bit is subjected to oscillatory, percussive, vibratory or axial thrust action.
EP-A-0197456 reveals a moling apparatus comprising a housing having a head for penetrating ground and thrust mans for driving said head through the ground.
The present invention is concerned with the provision of a moling apparatus which alleviates some or all of the disadvantages of existing devices.
Thus, according to the present invention, there is provided a moling apparatus comprising:
housing having a head for penetrating ground;
characterized by an anvil disposed in the housing connected to the head, a hammer disposed in the housing and spaced from the anvil by resilient restraint means, and
a vibrator unit spaced from the hammer and arranged to transfer vibration to the housing and the hammer; wherein the resilient restraint means and the space between the hammer and the anvil are so dimensioned that in operation in looser ground the hammer does not strike the anvil so that vibration transmitted to the housing causes fluidization of the surrounding ground and penetration of the apparatus; while in progressively harder ground the braking effect of the ground results in progressive compression of t
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patent: 3734460 (1973-05-01), Clarkson, Jr.
patent: 3741315 (1973-06-01), Hilton
patent: 4629299 (1986-12-01), Whiting et al.
patent: 4903784 (1990-02-01), Glaser
patent: 5031706 (1991-07-01), Spektor
Littlejohn Gavin Stuart
Rodger Albert Alexander
Aberdeen University
Paradiso John
Smith Scott A.
The University of Bradford
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