US2359213A - Means for cutting adits in chalk and allied strata - Google Patents

Description

Sept. 26, 1944. G, GARDNER 2,359,213

MEANS FOR CUTTING ADITs IN CHALK- AND ALLIED STRATA Filed NOV- 20, 1942 y p y z2' u (il. 1529.4'

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Patented Sept. 26, 1944 MEANS FOR CUTTING ADITS IN 'CHALK AND ALLIED STRATA James Geary Gardner,` Caterham, England l Application November 20, 1942, Serial No. 466,322 In Great Britain June 17, 1942 3 Claims. 262-33) This invention relates to means for cutting adits, channels, galleries or the like in chalk, limestone, compacted Iclay and kindred earth strata.

When cutting operations are commenced upon a face of -chalk or limestone it is normal to employ pneumatic drills or hammers and outline'a cavity so that the material enclosed by the out can be removed. This unfortunately shattersA the rock and loosens the formation for some 12 or 18 inches adjoining the cut and if the rock is unstratiiied and in nodular form, pillars and walls which might otherwise be used to support the roof are useless for such purpose and when galleries are cut for communication passages or caves or rooms excavated for war time shelters, it is frequently necessary to line the parts excavated with brick, and lin some cases provide pillars or props in addition.

'I'he object of the present invention is to provide means for cutting the rock instead of shattering it and so avoid the disruption of the conne wall and further to make a cut that is so clean that the wall surface produced has a ilat and even surface. With some rocks of the class mentioned, and especially with chalk there is sufircient water latent in the rock and expressed by the percussive cutting operation toform a slurry of the powdered material flowing from the chisel edge and the operation of cutting causes the slurry to flow backwards and relieve the tendency otherwise of the tool to wedge itself in and stick. For rocks that have insufficient latent moisture to form a slurry from the cut face, thetool is grooved or drilled and the cut supplied with water from some suitable external source. In such latter cases water is only required for the initial or rst two or three chisel incisions, the space left by the preceding cut or cuts accommodating the swarf material.

The invention consists in means for cutting adits, channels, galleries or passages in chalk, limestone, compacted clay and kindred earth strata, without shattering the formation, Whilst providing an even surface `and comprises a percussive tool having a `long and preferably slightly tapering and relatively thin chisel or jumper portion, said tool being deformed lengthwise intermediate its spigot and chisel portion to bring the penetrating blade out to or beyond the connes of the power driven percussive device adapted to operate said chisel, and to enable it to be driven forward tinto the rock face and incise by a series of abutting cuts, a predetermined boundary outline, grooves extending from the hilt to the tip of the blade for thelpassage of water for slurryng the powdered rmaterial during the cutting operation. The percussive hammer is pro- Vided with a sled for engagement with the wall of the out, thus aligning the offset blade of the tool with such wall, and the hammer tis preferably also provided with a lateral handle for holding the hammer against said Wall as the cutting proceeds.

In order that the invention may be .better understood reference is made to the accompanying drawing, wherein a' proposed embodiment of the invention is shown and wherein- Fig. 1 is a side elevation of the operating tool.

Fig. 2 is a plan of Fig. 1.

Fig. 3 shows the tool in operation cutting an adit or passage in the rock face and leaving an even sofiit as cutting takes place.

Fig. 4 is an illustration of the commencement of an adit or gallery with a wall partly incised to a predetermined contour, and a portion of the rock material within the incised boundary removed to show the soilit.

Referring to the drawing the cutting chisel or jumper A is adapted to be driven by a power ldriven reciprocating hammer B, see Eig, 3. The tool A has a normal spigot I, a shank 2, which is bent or deformed at 3 and then straightened and provided with a blade 4, the said blade being slightly tapered and provided at its operative end with a square cutting or powdering edge 5 atright angles to the blade 4. A handle 6 is formed integral with, or attached to, the shank 2, and a groove or grooves 'I is or are formed at the tool blade shoulder to carry water to the cutting edge. The tool is bent or offset at 3 an amount sufiicient to carry the shoulders 8 or hilt of the blade 4 to or outside of the confines of the tool B as shown in Fig. 3.

The method of use and manner of operation is as follows:

If C represents the rock or quarry face the configuration of the adit, gallery or passage ID (see Fig. 4) is marked out as at II and cutting commences, and the entire outline incised as at I2 by penetrating the rock by a series of successive abutting cuts, the rock at floor level being also undercut as shown at I3. This cutting operation provides a smooth and even soiit or face I4 as shown in Figs. 3 and 4. The rock material enclosed within the incised boundary can be excavated with a pickaxe, crowbar or other tool, or the device forming the subject'of this invention may be used for intercutting as shown at I5 .in Fig. 3.

of the tool, and allowed to dribble thereupon or down the face of the rock above the portion being cut. The water so supplied ndsits wayto the cutting face through the grooves 1 and forms a slurry which exudes at the rock face. After one or a few incisions has or have been made it is generally found that no further water is required, since the powdered rock of successive cuts is driven `or falls into the aperture or slit made.

by the `prior jcut. YSome rocks carry suflicient moisture to render the need of further waterV unnecessary( In Ythe operationV of cutting the tool is driven in up to the hilt or shoulder 8 and' i's thenv withdrawn for the next cut. Should the tooly stick then the operator seizes the handle 6", and by a combined twisting and withdrawing action jerks the tool backwards and out of its cut,

the tapering of the blade assisting this opera'- tion.

To assist left handed cutting theV power driven hammer B may be provided with a sled 20, and additional grip 2|, the sled being pushed against and along the eut walll as driving proceeds.

Should the tool meet int or stone in its penetration, the tool in the majority' of cases will shatter it, but an experienced quarryman will feel the stone and cut upwards or downwards to avoid it, and leave its removal, so as not to injure the surface, until excavation.

The chisel or jumper blade 4` is made of a width of face depending upon the power capable of being lexercised by a pneumatic or electric percussion tool. The blade length mayalso vary but an inward cut of 18 to 20 inches is a practical depth for the process of excavation.

The 'invention is not limited in itsv scope of application. Thus wells can be bored of any sectionV or underground chambers cut, railroad or canal tunnels can be cut in suitable strata such as chalkwith self-supporting roofs having a soflit that appears as if plastered. I claim;

1i. A tool for use in cutting adits and passages in 'chalk and like materials, comprising a flat chisel-shaped blade having a square cutting edge and-'of tapered section from hilt to tip, a spigot for attachment to a power percussion hammer, an offset portion intermediate the spigot and the blade, grooves extending from hilt to tip forY the passage of water, and a handle extending at right angles to the length of the tool.

2. A tool according. to claim I, in combination Wth'a percussion hammer having a sled for wall engagement and alignment.

'3. Atool according to claim 1, in combination with a percussion hammer provided with a sled for wall engagement and alignment, and with an additional lateral handle for left hand cutting.

JAMES` GEARY GARDNER.

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