AU8339391A - Splitting apparatus - Google Patents

Description

SPLITTING APPARATUS This invention relates to splitting apparatus. This invention has particular but not exclusiv application to splitting apparatus for splitting concrete o rock in demolition or mining applications, and fo illustrative purposes reference will be made to suc application. However, it is to be understood that thi invention could be used in other applications, such as i quarrying.

In general, the prior art of splitting rock, concret or the like has involved the use of either composition having a useful volumetric expansion or hydraulic pressure i boreholes provided along the desired cleavage plane. Compositions which have found such use include cementitiou grouts and compositions of burnt lime (anhydrous calciu oxide) wherein the expansion of the composition occurs upo hydration. Such compositions have the inherent disadvantage of difficulty of handling, particularly in wet environments, and lack of controllability.

Hydraulic splitting has generally utilized a probe o conduit for introducing liquid and/or gas under pressure to the bottom of a borehole, the borehole being plugged by a plug or the shank of the condui to contain the pressure. This manner of hydraulic splitting suffers from the inherent disadvantage that, in fractured strata, the hydraulic fluid may be lost to the strata without imparting a clear separating force.

In more recent times, several mechanical and hydraulic apparatus have been developed for use. For example, French Patent specification N. FR 2615913-A discloses a radial expansion rock splitting jack comprising a cylinder of separated arcuate panels which move radially outward under hydraulic pressure di .ributed to the plates by rubber wall tubes which expand radially to apply force on the panels. This apparatus suffers from the inherent disadvantage of expense and complexity in an attempt to provide reusability, whereas in practical use the rubber members will often fail after a single use. USSR Patent Specification No. SU1218106-A discloses a rock splitter adapted to split along a boreholes line usin expansion of rods featuring an inverted cone end fo contacting bevels on inside of expanding cheek pairs. The expandable cheeks are forced into the rock and hydraulic pressure applied to the plugged borehole fluid which is sufficient for separating a block from the massive surrounding. This apparatus again has the disadvantage of other prior art methods where the hydraulic fluid contacts the strata and has the additional disadvantage of requiring hardened and/or high tensile steel components, thus adding to the cost of manufacture.

West German Patent Specification No. DE3416957- discloses a rock splitter with a hydraulically driven sliding wedge which has pressure jaws, each with two pairs of parallel leaf springs on opposite sides of the sliding wedge. Flexible members between the top ends of the springs and the body of the hydraulic ram permit limited upward movement of the springs, together with the jaws. Again, this apparatus is expensively manufactured with a view to providing reusability whereas in practical reality, the failure rate of the apparatus is high due to the aggressive operating environment.

Australian Patent Specification No. 35029/84 discloses an inflatable cartridge assembly for well packin or rock splitting. The inflatable cartridge assembly is fo delivering high pressures to the inside surface of a aperture or bore, and comprises a mandrel having an axiall non-extensible core and two end abutments. An inflatable an radially expandable elastomeric sleeve is positioned aroun the mandrel and is bonded at each end to the respective en abutments. An aperture in the mandrel permits admission of pressurised fluid to the sleeve interior to expand th sleeve. The apparatus is described as safer than explosive when used as a splitter of hard brittle materials and is les complicated and less expensive than conventional cartridg assemblies. The assembly is usable at lower pressures fo well packing and higher pressures for in rock splitting. The apparatus disclosed in 35029/84 carries with i the disadvantage that the presence of the mandrel results i apparatus with little ability to relieve stress by limite elongation under inflation pressure. Accordingly, i practice the apparatus has a tendency to premature failure a the bonded ends.

The present invention aims to alleviate the abov disadvantages and to provide splitting apparatus which wil be reliable and efficient in use. Other objects an advantages of this invention will hereinafter becom apparent.

With the foregoing and other objects in view, thi invention in one aspect resides broadly in splittin apparatus includings- an elongate housing having an inwardly disposed wal portion; closure means for sealing the ends of said housing, and a passage for admission of a pressurizing fluid t said housing, whereby pressurizing said housing displace said wall portion to expand said housing.

The housing may comprise an substantially tubula body, preferably having a wall of constant thickness. Th tubular body may be of any suitable material such as metal o synthetic polymer, with it being preferred in the interests of economy and ease of working to produce the tubular bod from welded steel tube.

Preferably, the inwardly disposed wall portion of the housing comprises a longitudinal depression extending along substantially the full length of the housing such that the perimeter of the transverse cross-section of the housing exceeds the circumference of the smallest circle through which the cross-section may pass. In order to reduce the complexity of the apparatus and to minimize the stresses associated with the use of small radii of curvature, it is preferred to utilize a single longitudinal depression, although it is also envisaged that a plurality of depressions may be utilized. The ends of the preferred tubular housing may be sealed by any suitable sealing means such as by welding, bonding or any other means determined by those skilled in the art. However, it is preferred that the ends of the tubular housing be sealed by the introduction of a plug member adapted to sealably trap an end section of the tubular housing within a collar or the like. Preferably, the plug member is inserted within the bight of the inwardly disposed wall portion at the end of the housing such that the inner surface of the wall of the housing is closed onto itself against the collar.

The passage for admission of pressurized fluid is preferably provided at the outer end of the apparatus and may be provided in an end region of the housing, or alternatively in the preferred plug member or collar. The passage may take any form consistent with its function of permitting the admission of pressurized fluid and will be determined by the method of delivery and type of fluid. For example, the passage may include a threaded portion for connection to a high pressure hose or the like, or alternatively may include an aperture associated with sealing and locking means suitable for cooperation with, for example, quick release high pressure couplings.

The use of such plug members and collars as sealing means is preferred over welding to avoid the disadvantage of cracking at the welds before maximum splitting pressure is reached, the undesirable cracking being caused by stress concentration at the martenεitic boundaries of the welds.

Accordingly, in a further aspect, this invention resides in splitting apparatus including::- an elongate housing having a longitudinally disposed, inwardly disposed wall portion extending to one end of said housing; a collar member adapted to fit about said end of the housing; a plug member disposed in the bight of said inwardly disposed wall portion at said end to sealably close the inner surface of said end onto itself, and a passage for admission of a pressurizing fluid said housing.

Preferably, the housing is of substantially circul cross section such that the apparatus may be inserted in borehole provided in the substrate to be split. In order provide this substantially circular cross section, it preferred that the inwardly disposed wall portion be roll into the housing such that the interior of the housing adop an approximately kidney shape in cross section. This form rolled inwardly disposed wall portion is also preferred f its lack of abrupt curves or angles, thereby minimizing wo hardening and brittleness during the rolling process. T inwardly disposed wall portion is preferably consisten throughout the length of the stock used to form the housin such that production costs are minimized.

Preferably, a collar is provided at both ends of th housing. The collars may take any form consistent with thei function of providing a reactive inner surface upon which th end of the housing may be pressed closed by the insertion o the plug member in the end of the inwardly disposed wal portion. In one preferred embodiment of the presen invention the collars comprise stock steel tube of interna diameter approximating the outside diameter of the housing The collars may be of a size that they may be pressed ont the ends of the housing or alternatively the collars may be loose fit, the clearance between the housing and the colla being taken up by the expansion of the housing outsid diameter upon insertion of the plug member.

The collars may be identical at each end. However it is preferred that the outer end of the apparatus b provided with a collar which is longer than that provided a the inner end. The longer outer collar is preferred for th reason that the outer end of boreholes tend to taper in t the nominal borehole diameter, and the extra collar lengt ensures that the housing does not expand uselessly into thi wider part of the borehole.

The passage preferably comprises an aperture bore through the outer collar and continued through the wall o the housing to the interior thereof to admit hydraulic fluid or gas under pressure. To this end the aperture is preferably provided with a thread or the like to permit attachment of a pressure conduit, it being preferred that the aperture be provided with the "quick thread" type hydraulic connection. Where threaded attachment of the pressure conduit to the apparatus is undesirable, other connection means may be provided. For example, a clamping member may be provided with high pressure sealing means adapted to sealably engage a plain or profiled said aperture provided through the collar. Of course, if desired, the fluid passage may be provided through the plug member.

Preferably, the inner end of the outer collar is provided with a flared portion to prevent the outer collar from passing into the borehole at its nominal diameter, whilst ensuring that the housing is substantially inserted therein. -Of course this characteristic may be provided by any other suitable means such as by means of a stop or the like formed or attached to the housing or the outer collar. The flaring of the inner end of the outer collar is also desirable since this eliminates a sharp rim about which the expanding housing would otherwise^" wrap on a small radius, resulting in stress concentration and possible failure at the bend. The flare results in the expanding housing, restrained against expansion within the collar, making a smooth and gradual transition from the unexpanded portion to the fully expanded portion.

The plug member may take any form consistent with the function of compressing the material of the housing against the inner surface of the collar to seal the end of the housing. Preferably the plug member takes the form of a substantially cylindrical billet adapted to be pressed into the bight of the inwardly disposed wall portion, and being of a diameter selected such that insertion of the plug member sealably closes the inner surface of the housing and compresses the housing against the inner surface of the collar.

Preferably, the leading end of the plug member is tapered to assist in the insertion process. It als preferred that the angle of the taper be so chosen t minimize the creation of sharp bends of small radius in th wall of the housing at the sealed end. Typically, the angl of the taper included with the longitudinal axis of the plu member may be less than 60°.

Preferably, the length of the plug member is selecte that the binding force generated between the cylindrica surface of the plug member and the wall of the housin exceeds the force tending to expel the plug member generate by internal pressure acting on the housing wall ends in use By such selection of length the plug member may remain hel in the apparatus without resort to additional binding mean such as welding or bonding. It is preferred that the plug member be of les length than the collar to ensure that the stresses generate by insertion of the plug member do not extend substantiall to the housing at the region of the inner end of the collar. In a further aspect, this invention lies in a metho of manufacturing a rock splitter or the like and includin the steps of:- roll forming a longitudinal, inwardly disposed wall portion into a tubular member to form a housing; pressing a collar on to an end of said housing; pressing a substantially cylindrical plug member into said collar such that the plug member enters the bight of the inwardly disposed wall portion, whereby the inner surface of the wall of the housing is sealably closed onto itself and is compressed against the inner surface of the collar, and providing a passage for the introduction of pressurized fluid to the interior of said housing.*

Preferably, the tubular stock comprises continuous roll formed welded steel tube such as may be produced by continuously rolling steel strip of appropriate width, thickness and grade to form a tubular shape, followed by high frequency induction heating of the strip edges to forge welding temperature and forge welding the edges by applying pressure through squeeze rolls. The welded tube of circular cross section is preferably quenched to equilibrate temperatures throughout the section. The inwardly disposed wall portion is preferably roll formed into the continuous welded tube stock by a rolling wheels configured such that the inner surface of the tube at the deepest part of the inwardly disposed wall portion is still just clear of the inner surface diametrically opposed thereto, to ensure a continuous and unitary space within the resultant housing. The inwardly disposed wall portion is also preferably rolled such that the resulting housing stock is of approximately circular cross section, and such that, when collars are pressed onto the housing the outer longitudinal edges of the inwardly disposed wall portion approximately meet.

The continuous housing stock is preferably cut into desired lengths by any suitable means including flying cut off means such as a shear, a cold saw or a hot saw.

The outer collar is preferably cut from tubular stock and flared by any suitable means at its proposed inner end. For example, the flare may be produced by pressing using an appropriate former or may alternatively be produced by rolling. The degree of flare introduced may of course vary according to the wall thickness of the apparatus, the borehole size and other factors. It is envisaged that in most applications the flare will ensure that a maximum collar outer diameter of greater than the unexpanded diameter of the substantially cylindrical housing will be produced, such that the housing may pass into the borehole whilst the flared portion of the collar engages the taper of the borehole mouth at some distance in from the outer extremity of the borehole. The flare will also generally be of a radius to minimize the chance of apparatus failure near the collar caused by stress concentration about an unduly sharp rim of the collar.

The collar at the inner end of the apparatus is of course preferably of a maximum dimension no greater than that of the housing such that the inner collar may pass to the bottom of a minimum sized borehole. Since the apparatus in use is substantially supported in expansion against the borehole for all of its length except for that portion near the mouth of the borehole, it is not considered that flarin of the inner end of the inner collar is as important as for the outer collar. However, it is envisaged that the inner collar may be advantageously flared somewhat to assist in the preferred pressing operation for assembling the collar to the housing.

The cylindrical plug members may take any form consistent with their function of sealing the end of the housing by compressing the bight of the inwardly depending wall portion of the housing to close the inner surface of the housing and press the flattened housing wall against the inner surface of the collar. Preferably, the plug member is turned from round rod stock or the like and preferably comprises a conical portion and a cylindrical portion of sufficient swage or frictional grip to the material of the housing to avoid expulsion from the nd of the apparatus as pressurized fluid is supplied to the housing. The plug member is preferably pressed into the end of the inwardly disposed wall portion by the use of hydraulic presses or the like, the use of a pressing lubricant being also preferred.

The passage for the introduction of pressurized fluid may take any form consistent with the function of permitting the attachment of the apparatus to a source of such a fluid, with it being preferred for the reason of physical simplicity and robustness of the connection to drill a passage through the cylindrical surface of the collar and through the wall of the housing to the interior thereof at a point not closed by the plug member. The passage is preferably tapped with a thread or other suitable fixing means to permit connection to pressurizing apparatus.

The apparatus in use may be inflated with any suitable pressurizing fluid including expanding fluid compositions, high pressure gases and hydraulic liquids. Preferably, in the interest of efficiency and to eliminate the possibility of explosive disintegration of the apparatus with the attendant shrapnel risk, it is preferred to use a substantially incompressible hydraulic fluid which substantially fills the cavity. One advantage of preferred apparatus in accordance with the present invention relates to the fact that the plug member pressed into each end of the apparatus to sealably close the housing is not directly exposed to the internal pressure of the apparatus in use. Accordingly, the swage length of the plug member may be reduced below that which would be necessary to plug the end of the interior of the housing directly. The reason for this is that where the housing is plugged directly, the axial force applied to the plug member and tending to eject the plug member in use is the product of the pressure applied to the end of the plug member and the transversely projected area of the plug member exposed to this pressure. Conversely, where the plug member is inserted in the end of bight of the inwardly disposed portion, the applied pressure exerts a force against the deformed end portion of the wall of the housing, which force is countered by a reaction force from the collar, a radially directed reaction force transmitted to the plug member through the wall, an axial component of reactive force from the swage or friction of the cylindrical part of the plug member, again transmitted through the wall, and the inherent resistance of the wall material to deformation. As the pressure increases each of the first three forces will increase, the proportions by which the variable forces increase being largely dependant upon the angle of taper of the plug member affecting the axial and radial components of the reactive force from the plug member. In any case, the axial force tending to eject the plug member is demonstrated to be considerably less than that applied to a plug member inserted in the end of the cavity.

Accordingly, in a further aspect, this invention resides in a method of sealing the end of a substantially tubular body including the steps ofs- forming a longitudinal, inwardly disposed wall portion at the end of said tubular body; pressing a collar onto said end, and pressing a plug member into the bight of said inwardly disposed wall portion such that the inner surface of said inwardly disposed wall portion is forced into sealin contact against the inner surface of the remainder of th wall.

Preferably, the diameter of the plug member an internal diameter of the collar is selected such that, for particular combination of tube diameter and wall thickness the edges of the inwardly disposed wall portion substantiall meet within the collar when the plug member is full inserted, such that the radial compressive forces maintainin the seal are equally distributed about the collar. Thi preferred feature maximizes the grip between the collar an the wall, and the wall and the plug member to minimize th chances of failure under pressure.

In order that this invention may be more easil understood and put into practical effect, reference will no be made to the accompanying drawings which illustrate a preferred embodiment of the invention, wherein:-

FIG. 1 is a perspective view of a rock splitter in accordance with the present invention; FIG. 2 is a partial longitudinal cross-section of the outer end of the rock splitter of FIG. 1;

FIG. 3 is a partial longitudinal cross-section of the inner end of the rock splitter of FIG. 1 ; FIGS. 4 and 5 are an end view of stages of production of the rock splitter of FIG. 1;

FIG. 6 is an end view of the rock splitter of FIG. 1, and

FIG. 7 is an alternative pressure coupling adapted for use in conjunction with apparatus in accordance with the present invention. In the figures, there is provided a rock splitter 10 comprising a tubular housing 11 having an inner end collar 12 and an outer end collar 13. The tubular housing 11 is provided with a longitudinal inwardly disposed portion 14 resulting in a considerable amount of the wall 15 being turned into the cavity 16 defined by the housing 11. The circumference of the housing 11 is accordingly considerably less than the length of the perimeter of its cross section such that inflation of the rock splitter 10 may apply force to the walls of a borehole to which it is fitted.

The collars 12, 13 are of a lesser diameter than that of the housing 11 such that when the collars are installed on the ends of the tubular housing 11 the diameter at 17 of the tubular housing is further reduced. In general, the reduction in diameter of the housing 11 will approximate double the wall thickness of the collars 12, 13. This provides for a rock splitter that is of consistent diameter along its length such that it may be fitted to boreholes of a diameter close to the diameter of the housing 11. The configuration of the inwardly disposed portion 14, the diameter of the collars 12, 13, and the wall thickness of the housing 11 are all selected such that the rims 20 of the inwardly disposed portion 14 meet within the collars 12, 13 when the latter are installed on the housing 11.

The outer end collar 13 is provided with a flared inner end 21 which assists in the fitting of the collar 13 to the end of the housing 11 and also provided a stop to prevent the apparatus 10 from being inserted too far into a borehole by engaging the inner portion of the usually tapered mouth of the borehole.

The ends of the housing 11 are sealed by the insertion of solid cylindrical plug members 22 into the ends 23 of the inwardly disposed portion 14 such that the inner wall 24 of the inwardly disposed portion 14 is pressed into sealing contact with the remainder 25 of the inner wall of the housing 11, thereby sealing the cavity 16. The plug members 22 are provided with 45° tapers 26 which assist i both pressing the plug members 22 into the ends 23 of the inwardly disposed portion 16 and ensuring that the wall at 30 of the housing 11 is not unduly stressed by distortion about a sharp edge.

The outer collar 13 has drilled through the side wal thereof an aperture 31 which is continued through the wall o the housing 11 to provide fluid communication between th outside of the apparatus and the sealed cavity 16. Th aperture 31 is provided with a threaded portion 32 for th attachment of a hydraulic or compressed gas supply. In manufacture the housing 11 is produced i continuous lengths from steel strip which is r lied to tubular shape and welded along the join. The inwardl disposed portion 14 is then rolled into the housing stock an the resulting rolled stock cut into suitable lengths. Th collars 12, 13 are then pressed onto the ends of the housin 11, using a pressing lubricant where necessary. The plu members 22 are turned from rod stock and provided with thei taper 26. The plug members 22 are then pressed into the end 23 of the inwardly disposed portion 14 until the inner wal surface portions 24 and 25 of the end of the housing ar pressed into sealing con- ct with each other against th reactive force of the collars 12, 13.

In use, the rock splitting apparatus is inserted in borenole of only slightly larger diameter than the diamete of the housing 11. The borehole may be one of a series o boreholes defining a desired cleavage line. The singular o plural apparatus is then connected at aperture 31 to a sourc of hydraulic fluid which may be pressurized to a pressur sufficient to cause inversion of the inwardly dispose portion 14, thereby increasing the diameter of the apparatus and providing a radially outwardly directed force against the rock or the like substance to be cleaved. The pressure may then be increased to effect cleavage. In the embodiment of FIG. 7, the attachment of the source of pressurizing fluid is provided by a quick release fitting 40 comprising a fixed clamping member 41 having a mating surface 42 adapted to conform to the outer surface of the collar 12. A movable clamping member 43 having a similar mating surface 44 is slidably mounted to the fixed clamping member 41 on guide rods 45, and is retained on the guide rods 45 by a fixed end plate 46. A threaded operating member 47 is threadably engaged through the end plate 46 and is adapted to bear on the back of the movable clamping member 43. The operating member 47 is manually rotatable by means of a T- handle 50.

The fixed clamping member 41 is provided with a pressure coupling 51 threadably engaged through the wall of the member 41 and retained therein by a lock nut 52. The outer end of the coupling 51 is adapted to be connected to a conventional flexible high pressure hose or the like. The inner end of the coupling 51 is provided with a pilot end 53 adapted to guide the coupling into an unthreaded aperture provided through the collar 12, and a urethane seal adapted to make sealing contact with a corresponding sealing portion provided on said collar 12.

In use, the quick release fitting 40 is generally left attached to the high pressure hose such that the fitting 40 may be readily moved from apparatus to apparatus along the borehole line. Alternatively, a plurality of fittings 40 may be connected to a manifold of hoses for connection simultaneously to a plurality of splitting apparatus. The quick release fitting 40 is in use loosened and slipped over the end of the collar 12 and the pilot end 53 is engaged with the aperture in the collar. The T-handle 50 is then turned to tighten the clamping members 41, 43 thereby creating a seal between the pressure coupling 51 and the collar 12 by means of the urethane seal 54.

It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as defined in the claims appended hereto.

Claims (18)

1. Splitting apparatus i ling:- an elongate housing having an inwardly disposed wal portion; closure means for sealing the ends of said housing and a passage for admission of a pressurizing fluid t said housing, whereby pressurizing said housing displace said wall portion to expand said housing.

2. Splitting apparatus according to Claim 1, wherei said elongate housing comprises a substantially tubular bod of welded steel tube.

3. Splitting apparatus according to Claim 2, wherei said inwardly disposed wall portion of the housing comprise a longitudinal depression extending substantially the ful length of the housing such that the perimeter of th transverse σross-secti _n of the housing exceeds th circumference of the smallest circle through which the cross section may pass.

4. Splitting apparatus according to Claim 1, wherei said sealing means comprises a plug member adapted t sealably trap an end portion of said housing within a collar or the like.

5. Splitting apparatus according to Claim 4, wherein said plug member is inserted within the bight of the inwardly disposed wall portion at the end of the housing such that the inner surface of wall of the housing is closed onto itself to effect sealing of said housing.

6. Splitting apparatus including:- an elongate housing having a longitudinally directed, inwardly disposed wall portion extending to one end of said housing; a collar member adapted to fit about said end of the housing; a plug member disposed in the bight of said inwardly disposed wall portion at said end to sealably close the inner surface of said end onto itself, and a passage for admission of a pressurizing fluid to said housing.

7. Splitting apparatus according to Claim 6, wherein said housing is of substantially circular cross section such that the apparatus may be inserted in a borehole provided in the substrate to be split.

8. Splitting apparatus according to Claim 7, wherein said inwardly disposed wall portion is rolled into the housing such that the interior of the housing adopts an approximately kidney shape in cross section.

9. Splitting apparatus according to Claim 6, wherein the housing is provided with a collar at each end thereof, the outer end collar being longer than that provided at the inner end.

10. Splitting apparatus according to Claim 9, wherein said passage comprises an aperture bored through said outer collar and continued through the wall of the housing to the interior thereof.

11. Splitting apparatus according to Claim 9, wherein the inner end of said outer collar is provided with a flared portion to prevent the outer collar from passing into the borehole at its nominal diameter.

12. Splitting apparatus according to Claim 6, wherein said plug member takes the form of a substantially cylindrical billet adapted to be pressed into said bight and being of a diameter selected such that insertion of the plug member sealably closes the inner surface of the housing and compresses the housing against the inner surface of the collar.

13. Splitting apparatus according to Claim 12 wherein the leading end of the plug member is tapered t assist in the insertion process, the angle of the taper bein chosen to minimize the creation of sharp bends of smal radius in the wall of the housing in the region of the plu member.

14. Splitting apparatus according to Claim 13 wherein the length of the plug member is selected such tha the binding force generated between the cylindrical surfac of the plug member and the wall of the housing exceeds th force tending to expel the plug member generated by interna pressure acting on the housing wall ends in use.

15. Splitting apparatus according to Claim 6 wherein said plug member is shorter than said collar suc that the stresses generated by insertion of the plug membe do not extend substantially to the housing at the region o the inner end of the collar.

16. A method of manufacturing a rock splitter or th like and including the steps of:- roll forming a longitudinal, inwardly disposed wal portion into a tubular member to form a housing; pressing a collar on to an end of said housing; pressing a substantially cylindrical plug member int said collar such that the plug member enters the bight of th inwardly disposed wall portion, whereby the inner surface o the wall of the housing is sealably closed onto itself and i compressed against the inner surface of the collar, and providing a passage for the introduction of pressurized fluid to the interior of said housing.

17. A method of sealing the end of a substantially tubular body including the steps of.- for ing a longitudinal, inwardly disposed wall portion at the end of said tubular body; pressing a collar onto said end, and pressing a plug member into the bight of said inwardly disposed wall portion such that the inner surface of said end is sealably closed onto itself.

18. Splitting apparatus substantially as hereinbefore defined with reference to the accompanying drawings .