Earth working – With drive means for tool or cleaner – Tool driven about axis transverse to draft line
Reexamination Certificate
2000-02-03
2001-02-06
Novosad, Christopher J. (Department: 3671)
Earth working
With drive means for tool or cleaner
Tool driven about axis transverse to draft line
C172S123000, C172S810000, C172S548000, C089S001130
Reexamination Certificate
active
06182769
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for rapid clearance of landmines lying freely on the surface or buried in the upper ground layer, including both small anti-personnel (AP) mines and larger anti-vehicle and anti-tank mines.
BACKGROUND OF THE INVENTION
For rapid clearance of routes through minefields the military have previously used primarily chain flails and mine ploughs. Theses are most appropriate for military purposes and have achieved far from the 100% clearance result that is desirable in civil mine clearance operations after a conflict is over. Civil mine clearing operations have thus been achieved by the time consuming and labor intensive method of using probes or, perhaps, mainly by the use of electromagnetic mine detectors. The latter are, in fact, very sensitive but there are AP mines that do not contain any metal at all and are thus not detected. Moreover, the number of false indications that have to be checked is always high, especially in areas where battles have occurred as there is always a multitude of fragments in the ground in such areas.
In latter years, however, increasing interest has been focused on mechanical mine clearance vehicles that operate in a similar way to the mechanical rotary cultivator principle. They have been shown to have good capacity, and although they cannot operate in all types of terrain they clearly constitute a positive addition to the field of mine clearing.
Many of these rotary cultivator type demining tools are designed with horizontal rotation shafts fitted with multi-disc cultivators, each disc usually being fitted with individual teeth around its periphery.
The basic concept for the rotary cultivator disc type of mine clearing device is described in WO 95/24604, while DE 4.442.135 describes a variant of the same basic concept in which the various discs incorporate very large teeth machined direct in the actual disc and with apertures to reduce the risk of damage in the event of mine detonations in or under the demining tool.
The objective with demining tools that function on the rotary cultivator principle is that they shall ‘chew’ the mines in their path into small fragments or cause the mines to detonate. In practice it has been shown that usually mines are made to detonate in or under the demining tool which is usually no problem in the case of AP mines, but anti-vehicle and anti-tank mines easily cause damage to the demining tool. Consequently, it should be easy to repair or replace.
In practice, however, the main problem with demining tools of the above rotary cultivator type has not been damage to the demining tool by mine detonations initiated, but that individual mines—especially small AP mines—can pass undamaged through the demining tool. Quite simply, it has been difficult to achieve the virtual 100% mine clearance effect necessary in civil mine clearing. The cultivator discs cannot be located too densely as the closer they are to each other the higher the machine power that is needed.
SUMMARY OF THE INVENTION
The objective of the present invention is to raise the clearance percentage of demining tools of the above mentioned basic type.
As a demining tool of the above rotary disc roller type works, the upper ground layer down to a predetermined depth the soil worked collects between the cultivator discs and this accumulated soil sometimes includes undamaged individual mines.
We have now—significantly—found that mines embedded in this accumulated soil between the cultivator discs can be made to detonate if we mount a number of impact devices in the form of impact segments between the cultivator discs. These impact segments co-rotate with the shaft of the rotary cultivator discs and are arranged in a plane parallel with the cultivator discs with several impact segments in one and the same plane with a space between each impact segment so that as impact segments in the same plane follow each other (in rotation) they work the accumulated soil between the cultivator discs. The number of such impact devices in each plane may be
2
-
10
, but preferably
5
-
10
. In the preferred design they also have a leading edge relative to their direction of rotation that is bevelled rearwards in the direction of rotation of the roller such that the section of the impact segment closest to the axis of rotation first meets the accumulated soil between the cultivator discs and the leading edge of each impact segment has a sawtooth form.
The design of the leading edge of each impact segment and the space between each impact segment in the same rotational plane results in working of the accumulated soil between each two adjacent cultivator discs while the intermittent agitation of the accumulated soil by the impact devices acts to trigger all types of pressure sensitive AP mines.
Practical tests with live mines in completely realistic conditions have shown that by supplementing an otherwise equivalent demining tool with the impact devices claimed in the present invention, the mine clearance capability is increased from approximately 95% to 99%.
REFERENCES:
patent: 5442990 (1995-08-01), Krohn
patent: 2632568 (1978-01-01), None
patent: 3127856 (1983-02-01), None
patent: 4442135 (1996-01-01), None
patent: 503 649 (1996-07-01), None
patent: 95/24604 (1995-09-01), None
patent: 97/38281 (1997-10-01), None
Bofors AB
Novosad Christopher J.
Pollock, Vande Sande & Amernick, R.L.L.P.
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