Method for assembling a down-the-hole drilling apparatus for plastic pipe drilling and a down-the-hole drilling apparatus

Abstract

The invention relates to a method for assembling a down-the-hole drilling apparatus for plastic pipe drilling and an apparatus assembled according to the method. The apparatus comprises a plastic pipe (2) with a drill unit (3), which comprises a casing shoe (8) and first drilling elements (4) for drilling a central hole and second drilling elements (5) for reaming the central hole for the plastic pipe (2), wherein the plastic pipe (2) is arranged to be pulled into the drilled hole by a force effect from the drill unit (3) and the casing shoe (8).The drill unit (3) and the plastic pipe (2) are connected to each other by a sleeve part (z) of the casing shoe (8), which has a radial (r) fastening arrangement (xl, x2), wherein the connection between them is formed by physically treating the plastic pipe (2) in the radial direction (r) along the length of the sleeve part (z), such that an immovable contact surface (KI, K2) is formed between the plastic pipe (2) and the casing (8) in the longitudinal direction (s).

Description

[0001] METHOD FOR ASSEMBLING A DOWN-THE-HOLE DRILLING APPARATUS FOR PLASTIC PIPE DRILLING AND A DOWN-THE-HOLE DRILLING APPARATUS

[0002] The invention relates to a method and an apparatus for assembling a down-the-hole drilling apparatus for plastic pipe drilling and a down-the-hole drilling apparatus, according to the preambles of the independent patent claims directed thereto.

[0003] FIELD OF THE INVENTION

[0004] Down-the-hole drilling is used for creating holes in soil, especially in rock or other hard earth materials, where typically a pneumatically operated hammer and a drill string, which comprises a drilling apparatus and a drill bit as well as drill pipes, are used for breaking the rock. The down- the-hole hammer belonging to the drilling apparatus operates directly at the bottom of the borehole and produces a powerful impact on the ground through the drill bit, which is further guided by the piping. The simultaneous rotation of the drill pipe enables efficient penetration of the rock. Down-the-hole drilling can be performed, for example, with conventional metal pipe drilling and by using an asymmetric wing bit to create the borehole.

[0005] BACKGROUND OF THE INVENTION

[0006] Down-the-hole drilling can also be performed in a manner that deviates from the aforementioned asymmetric wing bit technique. Finnish patent no. 95618 discloses a method in which the drill head of the drilling apparatus, located inside a casing part, i.e., a soil pipe or protective pipe, comprises a first body part, i.e., a pilot, and a ring-shaped second body part, i.e., a reamer, on whose drilling surfaces their drilling elements, such as bits or the like, are arranged. In this case, the first body part comprising the first drilling elements i s detached from the second body part comprising the reamer by pulling it out of the drilled hole alone after the drilling situation .

[0007] In the solution in question, said drilling elements are arranged for the drilling situation non-rotatably with respect to each other and locked in the longitudinal direction in both directions by means of an arrangement , according to a preferred embodiment of the invention, by means of a bayonet lock, wherein the locking occurs via release grooves provided longitudinally on the side surface of the first body part .

[0008] In connection with the drilling apparatus described above , a casing shoe is typically used at the end of the cas ing part , through which the casing part is pulled into the drilled hole by a force transmitted either from the pilot or the reamer . The prior art Figure 1 illustrates a structure where the casing part is pulled into the drilled hole by a force ef fect ( F) transmitted from the casing shoe via a connection element ( L ) between it and the reamer, i . e . , by two pulling shoulder arrangements located sequentially in the longitudinal direction in said parts .

[0009] Referring to the above , the assembly of the drill head according to Figure 1 is typically done in such a way that the elongated, sleeve-like casing shoe is cut longitudinally at a workshop during the installation phase and spread open, after which it is pressed closed around the reamer and welded at its cutting point back into a uni fied ring . The resulting weld seam, however, creates a weak point in the casing shoe , which poses a risk of fracture in the seam under di f ficult conditions . Disadvantages of this solution also include the associated extra work steps , as the casing shoe must be cut longitudinally, pressed closed onto the reamer, and finally welded back together.

[0010] Furthermore, for example, from patent EP 1144797, it is known to utilize a shrinking method for forming the connections between the casing shoe and a rotationally symmetric drill, wherein the casing shoe is compressed in the radial direction so that a locking projection on it engages with a corresponding locking recess in the drill. The connection method presented in the publication is, however, applicable only to a casing shoe external to the plastic pipe, and in such a case, it always requires a support structure inside the plastic pipe, which must then be removed after making the connection. Due to the requirement for an internal support, such a connection method is also very difficult to perform in a long pipe, which is why the installation of the casing shoe onto the plastic pipe is currently done with existing methods first on a shortened pipe, i.e., a so-called stub, after which the short pipe comprising the connections is further welded to a longer pipe for drilling.

[0011] It is also known in plastic pipe drilling to connect the casing shoe to the plastic pipe using a cutting attachment directly to the plastic pipe. The disadvantage of this structure, however, is that the casing shoe tends to continue its cutting motion during drilling due to the torque it generates, wherein in practice, the threaded casing shoe tends to continue threading into the pipe, and when using a toothed or grooved shoe, the additional cutting may break the connection during use.

[0012] PURPOSE OF THE INVENTION

[0013] Alongside traditional steel pipe drilling, it is possible to use plastic pipes. Particularly suitable applications for plastic pipe drilling include well drilling or tunnel roof reinforcement ( forepoling) . The advantage of using plastic pipes in drilling is that they are lighter compared to steel pipes , which also results in them having more economical transport costs and being easier to handle on the worksite . Additionally, a plastic pipe is signi ficantly cheaper than a corresponding steel pipe . A plastic pipe also does not rust , and when installed in the ground, it does not break, for example , the blades of crushers or drills when the ground is later worked or drilled . Furthermore , by using plastic pipes in well drilling, rusting o f the pipes is avoided . For example , in water wells , rust itsel f spoils the water, and when the pipe rusts through, surface water can enter the well , causing water contamination . In thermal wells , a rusted-through pipe allows surface water to mix with groundwater, which is a s igni ficant problem, especially in groundwater areas . For this reason, well drilling is prohibited in many groundwater areas , but by using plastic pipes , these problems can be solved .

[0014] However, there are problems associated with plastic pipe drilling, due to which it is not poss ible to utili ze it to the extent that there would be a need and potential for . This is due , for example , to the fact that current drilling arrangements require the use of a steel pipe at the beginning of the drilling, after which it is only possible to use a plastic pipe connected, for example , by a threaded j oint to the end of the steel pipe , and subsequently successively connected plastic pipes . On the other hand, there are al so solutions in use that are based on a threaded connection between a pre-threaded plastic pipe and a casing shoe .

[0015] Of the solutions mentioned above , the first one is not satis factory because it still requires the use of a steel pipe in the initial phase , after which one can only then utili ze prefabricated threaded plastic pipes . On the other hand, the use of pre-threaded plastic pipes has also proven to be exceedingly di f ficult in practice, because the threaded part of the plastic pipe connected to the steel casing shoe easily breaks due to the di f ferences of mutual threading shape deviations of the parts . The problems with using prethreaded plastic pipes are l ikely caused largely by the di f ferences between steel and plastic, for example , in terms of their strength and thermal expansion properties .

[0016] Pre-threaded plastic pipe connection systems have been further developed, for example , by using a connection piece threaded onto the plastic pipe and a very long connection arm on the casing shoe , which i s equipped with necessary elastic elements , such as damping O-rings . Despite this , a reliable connection between the casing shoe and the plastic pipe that can be implemented with reasonable costs is currently particularly challenging .

[0017] Furthermore , speci fically related to plastic pipe drilling, publication EP3175077B1 discloses a method and a down-the- hole drilling apparatus , wherein the connection of the casing shoe to the reamer and to the end of the plastic pipe is achieved by radially shrinking the casing shoe , which thereby creates both a rotating and longitudinally locked j oint with the reamer and, on the other hand, presses against the end of the plastic pipe over a suf ficiently long area . In this case , the plastic pipe used for drilling does not require special pre- fabrication, as the casing shoe is connected directly to its outer surface . Such solutions , however, require an internal support structure for the plastic pipe , such as a metal bushing, to achieve a reliable connection between the casing shoe and the plastic pipe , which must be removed from the pipe after the connection is made . This , in turn, leads to a situation where the length of the plastic pipe to be attached is limited, so that the support structure can be removed before actual use . Additionally, the force required to compress the metal casing shoe is high and requires a powerful press , meaning the connection can only be made in workshop conditions instead of field conditions .

[0018] All the types of arrangements described above thus require unnecessarily complex arrangements for implementing the connection between the casing shoe and the plastic pipe , which is why they increase manufacturing costs and signi ficantly complicate the use of the solutions in practical installation work .

[0019] There is still a need to develop the construction of a drilling apparatus comprising a rotationally symmetric pilot and reamer, especially for plastic pipe drilling, due to problems related to the use o f a conventional casing shoe , as the types of solutions described above for the mutual connection of the drill unit and the plastic pipe are unsatis factory .

[0020] DESCRIPTION OF THE INVENTION

[0021] The method for assembling a down-the-hole drilling apparatus for plastic pipe drilling and the down-the-hole drilling apparatus according to the present invention are intended to achieve a decisive improvement on the type of down-the-hole drilling apparatus assembly method and the actual down-the- hole drilling apparatus described above and thus to substantially raise the level of prior art prevailing in the field . To attain this obj ective , the method and the down- the-hole drilling apparatus according to the invention are mainly characteri zed by what is presented in the characteri zing parts of the independent patent claims directed thereto .

[0022] The most important advantages of the method and the down- the-hole drilling apparatus according to the invention include the simplicity of their assembly principle and structure . The functionality of a rotationally symmetric drilling apparatus , which has proven to be advantageous in practice , can be further improved by streamlining the assembly phases related to the assembly of the drill unit and the actual plastic pipe drilling without the problems identi fied in prior art , while signi ficantly reducing material costs . The invention enables the simpli fication of the installation of the casing shoe and the associated plastic pipe . In the method according to the invention, the connection of the plastic pipe into immovable contact with the casing shoe is achieved by physically treating the plastic pipe engaging with it , for example by compressing or expanding the plastic pipe against the surface of the casing shoe . To achieve an immovable connection, the casing shoe and / or the plastic pipe have fastening elements , such as serrations , shoulders , threads , ridges , friction surfaces , or the like , arranged on the casing shoe , which, when the plastic pipe is physically treated, engage into the surface of the plastic pipe , locking the connection in place .

[0023] Thanks to the invention, the drill unit can also be prepared in advance at a workshop by pressing or expanding the plastic pipe directly onto the casing shoe at the end of the plastic pipe , whereby, thanks to the treatment of the plastic pipe , it engages with the fastening elements of the casing shoe .

[0024] The method and apparatus according to the invention further enable the streamlining of production related to plastic pipe drilling . The connection between the casing shoe and the plastic pipe , manufactured according to the invention, can be reali zed utili zing shrinking or expansion techniques signi ficantly more simply than at present . Thanks to the method and the resulting simple structure , the invention can be applied to drill units and plastic pipes of varying si zes , while also optimi zing their wall thicknesses compared to traditional casing shoe constructions . Thanks to the invention, the connection between the drill unit and the casing part of the plastic pipe does not require the use of disproportionately large force when physically treating the plastic pipe instead of the casing shoe , enabling tools used for the connection between the casing shoe and the plastic pipe to be lighter and more economical . The invention further enables material savings and streamlining of assembly by avoiding, for example, assembly steps resulting from the longitudinal cutting of the casing shoe . Furthermore , thanks to the invention, in the method for assembling the down-the- hole drilling apparatus , there is no need to arrange separate support structures inside the casing shoe or pipe , as the casing shoe or its part acts as a support itsel f , unlike when compressing the casing shoe or its sleeve part against a plastic pipe , for example , with a radial press , where the plastic pipe must be supported in its internal space to achieve the connection .

[0025] Furthermore , an advantage of the method and down-the-hole drilling apparatus according to the invention is the possibility to use both an outer and an inner cas ing shoe in relation to the plastic pipe . The casing shoe can also be attached directly to a long pipe without the use of a separate , shortened pipe and its welding to a long pipe , which reduces and simpli fies the work steps . Thanks to this , the connection is easy to make even in field conditions , where the user of the drilling equipment can place the plastic pipe inside or outside the casing shoe without preshaping it , and form the connection between the pipe and the casing shoe with a pilot drill shaped for the purpose or a suitable lightweight tool , such as a conical or expanding mandrel , a bushing, or a radial press .

[0026] Other preferred embodiments of the method and down-the-hole drilling apparatus according to the invention are presented in the dependent patent claims directed thereto .

[0027] LIST OF FIGURES

[0028] In the following description, the invention is illustrated in detail with reference to the accompanying drawings , in which

[0029] Figure 1 shows a cross-sectional view of a prior art embodiment related to metal pipe drilling, wherein the mutual connecting elements between the casing shoe and the reamer are arranged with two longitudinally successive pulling shoulders on the parts ,

[0030] Figure 2 shows a cross-sectional view of an embodiment of the apparatus according to the invention with an external casing shoe ,

[0031] Figures 3a and 3b show a cross-sectional view of an embodiment of the apparatus according to the invention with an external casing shoe before the formation of the fastening area ( 3a ) and after it ( 3b ) , Figures 4a and 4b show a cross-sectional view of an embodiment of the apparatus according to the invention with an internal casing shoe , before the formation of the fastening area ( 4a ) and after it ( 4b ) ,

[0032] Figures 5a-5c show cross-sectional views of the steps of an embodiment of the method according to the invention for forming the locking arrangement of the casing shoe and the plastic pipe when us ing an external casing shoe and an internal mandrel ,

[0033] Figures 6a- 6c show cross-sectional views of the steps of an embodiment of the method according to the invention for forming the locking arrangement of the casing shoe and the plastic pipe when us ing an internal casing shoe and an external bushing,

[0034] Figures 7a-7c show cross-sectional views of the steps of another embodiment of the method according to the invention for forming the locking arrangement of the casing shoe and the plastic pipe when us ing an internal casing shoe and an external radial press ,

[0035] Figures 8a- 8d show exemplary connection principles of the casing shoe and the plastic pipe utili zed in the apparatus according to the invention . DETAILED DESCRIPTION OF THE INVENTION

[0036] The invention relates , first o f all , to a method for assembling a down-the-hole drilling apparatus for plastic pipe drilling .

[0037] The down-the-hole drilling apparatus has a dri lling device for performing drilling using a plastic pipe 2 with a drill unit 3 , which comprises a drilling arrangement at its drill head, such as first drilling elements 4 for drilling a central hole and second drilling elements 5 for reaming the central hole for the plastic pipe 2 . The dri lling elements 4 , 5 are , on the one hand, connected to each other for the drilling situation to transmit force for their j oint rotational movement , feed movement and / or percussion movement , and on the other hand, detachably connected to the plastic pipe 2 , at least so that the first drilling elements can be removed from the drilled hole . The plastic pipe 2 is arranged to be pulled into the drilled hole by a force ef fect , which is directed thereto from the drill unit 3 , such as from the second drilling elements 5 or from a cas ing shoe 8 connected to them in a manner transmitting force at least in the longitudinal direction s of the drilling device . The drill unit 3 and the plastic pipe 2 are connected to each other via the casing shoe 8 at the end I I of the dril ling arrangement , opposite to the drilling face P of the drill unit 3 , such as a sleeve part z of the casing shoe 8 , which has a radially r arranged internal fastening arrangement xl or an external fastening arrangement x2 , wherein by radially r expanding or compressing the plastic pipe 2 , a contact surface KI formed on the outer surface of the end I of the plastic pipe or a contact surface K2 formed on the inner surface of the plastic pipe i s created in the longitudinal direction s to pull the plastic pipe 2 into the drilled hole by the force ef fect transmitted from it . In this case , as a preferred embodiment of the invention, when using a casing shoe 8 that fastens to the outside of the plastic pipe 2 , the end I of the plastic pipe 2 is fitted substantially inside the casing shoe 8 , and further, when using an internal casing shoe 8 that fastens to the inside of the plastic pipe 2 , the end I of the plastic pipe 2 is fitted substantially outside the casing shoe 8 . In this context , as a preferred embodiment of the apparatus of the invention, the end I of the plastic pipe 2 is most suitably straight , i . e . , of the same diameter as its casing part .

[0038] As a preferred embodiment of the method of the invention, an internal fastening arrangement xl of the casing shoe , such as an internal thread, -pattern, -knurling, serration or shoulder arrangement or the like in the end of the sleeve part z , is prepared in particular with reference to figures 3a and 3b with an inner diameter DI to be fitted with the outer diameter dl of the end I of the plastic pipe 2 , wherein the mutual contact surface KI between the fastening arrangement xl and the end I of the plastic pipe 2 is formed by placing the sleeve part z provided with the fastening arrangement xl radially r over the end I o f the plastic pipe and thereafter expanding at least the end I of the plastic pipe 2 in the space inside the casing shoe 8 , whereby the fastening arrangement xl is brought radially r into contact with the outer surface of the end I of the plastic pipe 2 , at least partially pressing into it .

[0039] In an advantageous embodiment of the method according to the invention, an external fastening arrangement x2 of the casing shoe , such as an external thread, -pattern, -knurling, serration, shoulder arrangement or the like at the end of the sleeve part z , is prepared in particular with reference to figures 4a and 4b with an outer diameter D2 to be fitted with the inner diameter d2 of the end I of the plastic pipe 2 , whereby the mutual contact surface K2 between the fastening arrangement x2 and the end I of the plastic pipe 2 is formed by placing the sleeve part z provided with the fastening arrangement x2 radially r inside the end I of the plastic pipe and thereafter compressing at least the end I of the plastic pipe 2 from outside the casing shoe , whereby the fastening arrangement x2 i s brought radially r into contact with the inner surface of the end I of the plastic pipe 2 , at least partially pressing into it .

[0040] As a preferred embodiment of the method of the invention, the drill head of the drill unit 3 of the dri lling apparatus consists of a first body part 4a and a second body part 5a, for said body parts ' end surfaces forming the drilling faces P ; Pl , P2 , there are arranged the drilling elements of the first and second drilling elements 4 , 5 , such as a sol id cutting edge , separate bits , -inserts or the like .

[0041] The fastening arrangements xl , x2 are advantageously formed with reference to figures 3a-3b and 4a-4b, for example , by machining a toothing on the inner and / or outer surface of the sleeve part z , partially penetrating into the plastic pipe , wherein the teeth can be , for example , pyramid-shaped or otherwise triangular in cross-section, or straight or conical . Furthermore , the fastening arrangements xl , x2 can be grooves , shoulders , one or more threads formed in the longitudinal direction s , such as a straight or conical machine , flat , or trapezoidal thread and / or equivalent , a ridge , a rough friction surface , a form lock and / or equivalent . According to an advantageous embodiment of the method of the invention, the plastic pipe 2 i s brought into immovable contact with the casing shoe 8 by physically treating the plastic pipe 2 from its inside or outside .

[0042] As a further preferred embodiment of the method of the invention, the physical treatment of the plastic pipe 2 , whose inner diameter d2 is adapted such that it can be placed outside the sleeve part z of the casing shoe and its fastening arrangement x2 , is arranged such that the plastic pipe 2 is fitted outside the s leeve part z of the cas ing shoe 8 and its external fastening arrangement x2 and the plastic pipe 2 is treated at least partially along the length of the sleeve part z by compressing it , wherein the fastening arrangement x2 of the sleeve part z attaches immovably to the inner surface of the plastic pipe 2 , at least partially pressing into it .

[0043] On the other hand, as a preferred embodiment of the method of the invention, the physical treatment the plastic pipe 2 , whose outer diameter dl is adapted such that it can be placed inside the sleeve part z o f the casing shoe 8 and its fastening arrangement xl , is arranged such that the plastic pipe 2 is fitted inside the sleeve part z of the casing shoe 8 and its internal fastening arrangement xl , and the plastic pipe 2 is physically treated from its internal space by expanding it at least partially along the length of the sleeve part z of the casing shoe 8 and its fastening arrangement xl , whereby the fastening arrangement xl attaches immovably to the outer surface of the plastic pipe 2 , at least partially pressing into it . In this case , as a preferred embodiment of the method of the invention, when using a casing shoe 8 that fastens to the outside of the plastic pipe 2 , the outer diameter dl of the end I of the plastic pipe 2 is substantially adapted such that the plastic pipe 2 can be placed inside the cas ing shoe 8 and its fastening arrangement xl , and further, when using a casing shoe 8 that fastens to the inside of the plastic pipe 2 , the inner diameter d2 o f the end I of the plastic pipe 2 is substantially adapted such that the plastic pipe 2 can be placed outside the casing shoe 8 and its fastening arrangement x2 . In this context , as a preferred embodiment of the method of the invention, the end I of the plastic pipe 2 is fitted, depending on the situation, inside or outside the casing shoe 8 , and the plastic pipe 2 is treated accordingly physically from its inside or outside to form the outer contact surface KI or the inner contact surface K2 of the plastic pipe and to connect the plastic pipe 2 and the casing shoe 8 to each other .

[0044] As a preferred embodiment of the method of the invention, the physical treatment of the plastic pipe 2 , which has a larger inner diameter d2 than the sleeve part z of the casing shoe 8 and its fastening arrangement x2 , is performed using an external tool 7 for the plastic pipe 2 , such as a radial press 7b and / or a bushing 7a, wherein the dimensions of said tool are adapted such that it causes the plastic pipe 2 to be compressed against the fastening arrangement x2 of the sleeve part z of the casing shoe 8 .

[0045] As a further preferred embodiment of the method of the invention, the physical treatment of the plastic pipe 2 , which has a smaller outer diameter dl than the sleeve part z of the casing shoe 8 and its fastening arrangement xl , is performed using an internal tool 6 for the plastic pipe 2 , such as a conical mandrel , an expandable mandrel , or the like , wherein the dimensions of said tool are adapted such that it can be arranged in the space inside the plastic pipe and dimensioned such that it causes the plastic pipe 2 to expand in the radial direction r against the fastening arrangement xl of the sleeve part of the casing shoe 8 at the location of the casing shoe 8 .

[0046] As a further preferred embodiment of the invention, the plastic pipe 2 is arranged at its casing shoe 8 end to be larger in diameter than its casing part , such as conically expanding, expanding in a stepped manner, or the like , for fitting it outside the casing shoe 8 and / or its sleeve part z before being compressed against the casing shoe 8 and / or its sleeve part z . Furthermore , as a preferred embodiment of the invention, the plastic pipe 2 is arranged at its casing shoe 8 end to be smaller in diameter than its casing part , such as tapering, reduced in a stepped manner, or the like , for fitting it inside the casing shoe 8 and / or its sleeve part z before the plastic pipe 2 is expanded against the casing shoe 8 and / or its sleeve part z .

[0047] As a preferred embodiment of the method of the invention, the end of the plastic pipe 2 has the same diameter as its casing part , wherein the end of the plastic pipe is straight . In this case , it is possible to use a straight cut end of a plastic pipe for forming the connection with the casing shoe 8 . In this case , in the method of the invention, the end I of the plastic pipe 2 is f itted inside or outside the casing shoe 8 and an external force is applied to force it inside or outside the sleeve part z of the casing shoe 8 , whereby the end I of the plastic pipe 2 i s shaped by the ef fect o f the internal and external fastening arrangements xl , x2 used for fastening before said physical treatment of the end I o f the plastic pipe 2 .

[0048] As a preferred embodiment of the method of the invention, the plastic pipe 2 used is an essentially unprocessed raw pipe blank, which is advantageously made , for example , of plastic, such as PE , PEH- , PVC-plastic or the li ke , and / or of a reinforced plastic material , such as fiber-reinforced plastic or the like .

[0049] As a preferred embodiment of the method according to the invention, the sleeve part z provided with the fastening arrangement xl , x2 is arranged integrally with the opposite end I I of the second drilling elements 5 , such as the reamer, or of the casing shoe 8 . Furthermore , as a preferred embodiment of the invention, the plastic pipe is compressed or expanded over the entire length of the casing shoe 8 or, with reference to figures 3a, 3b, only along the length of the sleeve part z .

[0050] The invention relates on the other hand to a down-the-hole drilling apparatus , which has a drilling device for performing drilling using a plastic pipe with a dri ll unit 3 , which comprises at its drill head a drilling arrangement , such as first drilling elements 4 for drilling a central hole and second drilling elements 5 for reaming the central hole for the plastic pipe 2 . The dril ling elements 4 , 5 are connected to each other, at least in a drilling situation in a force transmitting manner, for their j oint rotational movement , feed movement , and / or percussion movement , and on the other hand, are detachably connected to the plastic pipe 2 to enable the removal of at least the first drilling elements 4 from the drilled hole . The plastic pipe 2 is arranged to be pulled into the drilled hole by a force effect, which is applied to it from the drill unit 3, such as from the first drilling elements 4 or the second drilling elements 5 or from a casing shoe 8 connected to them in a force transmitting manner at least in the longitudinal direction s of the drilling device. The drill unit 3 and the plastic pipe 2 are connected to each other at the opposite end II of the drilling arrangement, such as the first or second drilling elements 4,5 or the casing shoe 8, relative to the drilling surface P of the drill unit 3, with a sleeve part z, which has in the radial direction r an internal fastening arrangement xl or an external fastening arrangement x2, wherein by compressing or expanding the plastic pipe in the radial direction r against the casing shoe 8 and / or its sleeve part z, an essentially immovable contact surface KI, K2 is created along the outer or inner surface of the end I of the plastic pipe in the longitudinal direction s, for pulling the plastic pipe 2 into the drilled hole by the force effect transmitted from the drill unit 3.

[0051] As a preferred embodiment of the down-the-hole drilling apparatus of the invention, the drill head of the drill unit 3 of the drilling device 1 consists of a first body part 4a and a second body part 5a, the end surfaces of which form drilling faces P; Pl, P2, wherein drilling members, such as unitary cutting part, separate bits, inserts or the like are arranged on said drilling faces P; Pl, P2, of the first and second drilling elements 4, 5. An internal fastening arrangement xl or an external fastening arrangement x2, such as grooves, shoulders in the end of the sleeve part z, one or more threads formed in the longitudinal direction s, such as a straight or conical machine-, flat-, trapezoidal thread and / or the like, a ridge, a rough friction surface, a form lock and / or the like, is arranged in a pre-fabrication stage, before the connection of the drill unit 3 and the plastic pipe 2 to each other, with a diameter substantially matched with the diameter of the end I of the plastic pipe 2, for placing the plastic pipe inside or outside the casing shoe and / or its sleeve part for forming the connection.

[0052] As a preferred embodiment of the down-the-hole drilling apparatus of the invention, the sleeve part (z) , provided with the fastening arrangement (xl, x2) such as one or more grooves, shoulders, one or more threads formed in the longitudinal direction (s) , such as a straight or conical machine-, flat-, trapezoidal thread and / or the like, a ridge, a rough friction surface, a form lock and / or the like on the inner or outer surface of the sleeve part (z) , is arranged integrally with the end (II) of the second drilling elements (5) , such as the reamer, or of the casing shoe (8) . Furthermore, as a preferred embodiment of the down-the-hole drilling apparatus of the invention, its connection between the casing shoe (8) and the plastic pipe is also suitable for use with a drill unit (3) , which comprises, instead of the first drilling elements (4) and second drilling elements (5) , a drill unit comprising only one set of drilling elements, such as a drill unit provided with an eccentric drill bit, wherein the drill unit does not comprise a separate reamer.

[0053] In a further advantageous embodiment of the down-the-hole drilling apparatus according to the invention, the plastic pipe (2) used in the drilling is an essentially unprocessed raw pipe blank, which is advantageously made from a material such as plastic, for instance PE, PEH-, PVC-plastic or the like, and / or a reinforced plastic material, such as fiber- reinforced plastic or the like. It is obvious that the invention is not limited to the embodiments presented or described above but can be modi fied within the framework of the basic idea of the invention according to the requirements of the respective needs and circumstances , such as the soil of the drilling site . Thus , it is clear that the structures of the drilling apparatuses as described in the accompanying drawings vary greatly in practice , simply by being implemented with di f ferent diameters . As the drilling apparatus , it is naturally possible to use , instead of the types of embodiments shown in the accompanying drawings , also other drilling apparatuses suitable for a similar purpose . Furthermore , for the method and apparatus of the invention, it i s not particularly signi ficant how the connection arrangement between the first and second drilling elements is implemented, as a wide variety of solutions can be utili zed for the force transmission arrangements between them, especially with regard to the f lushing flow and the fastening arrangement . The invention i s naturally also applicable to the use of a single-piece drilling apparatus which does not have a separate reamer and pilot .

Claims

Claims :

1. A method for assembling a down-the-hole drilling apparatus for plastic pipe drilling, wherein the apparatus comprises a drilling device for performing drilling using a plastic pipe (2) with a drill unit (3) , which comprises a casing shoe (8) and a drilling arrangement at the drill head of the drill unit, such as first drilling elements (4) for drilling a central hole and second drilling elements (5) for reaming the central hole for the plastic pipe (2) , said drilling elements (4, 5) being connected to each other to transmit force at least in a drilling situation for their joint rotational, feed and / or percussion movement, and on the other hand, being detachably connected to the plastic pipe (2) to enable the removal of at least the first drilling elements (4) from the drilled hole, wherein the plastic pipe (2) is arranged to be pulled into the drilled hole by a force effect which is applied to it from the drill unit (3) , such as from the second drilling elements (5) or from a casing shoe (8) connected to them to transmit force at least in the longitudinal direction (s) of the drilling device, characterized in that the drill unit (3) and the plastic pipe (2) are connected to each other by a sleeve part (z) of the casing shoe (8) at an end (II) opposite the drilling face (P) of the drill unit (3) , said sleeve part (z) having a radial (r) fastening arrangement (xl, x2) , wherein the plastic pipe (2) is physically treated in the radial direction (r) by compressing the plastic pipe with an external tool (7) or by expanding the plastic pipe (2) with an internal tool (6) at least along the length of the sleeve part (z) such that the plastic pipe (2) is pressed against the casing shoe (8) , whereby an immovable contact surface (KI, K2 ) is formed between them in the longitudinal direction(s) for pulling the plastic pipe (2) into the drilled hole by the force effect transmitted from the drill unit (3) .

2. A method according to claim 1, characterized in that the sleeve part (z) of the casing shoe (8) comprises an internal fastening arrangement (xl) , which is prepared to be substantially fitted to the outside of the end (I) of the plastic pipe (2) , wherein the mutual contact surface (KI) between the fastening arrangement (xl) and the end of the plastic pipe (2, I) is formed by placing the end (I) of the plastic pipe (2) in the radial direction (r) inside the sleeve part (z) provided with the fastening arrangement (xl) and thereafter expanding the end (I) of the plastic pipe in the radial direction (r) towards the fastening arrangement (xl) , such that the fastening arrangement (xl) fastens to the outer surface of the end (I) of the plastic pipe (2) , at least partially pressing into it.

3. A method according to claim 1, characterized in that the sleeve part (z) of the casing shoe (8) comprises an external fastening arrangement (x2) , which is prepared to be substantially fitted to the inside of the end (I) of the plastic pipe (2) , wherein the mutual contact surface (K2) between the fastening arrangement (x2) and the end (I) of the plastic pipe (2) is formed by placing the end (I) of the plastic pipe (2) in the radial direction (r) outside the sleeve part (z) provided with the fastening arrangement (x2) and thereafter compressing the end (I) of the plastic pipe in the radial direction (r) towards the fastening arrangement (x2) , such that the fastening arrangement (x2) fastens to the inner surface of the end (I) of the plastic pipe (2) , at least partially pressing into it.

4. A method according to any of the preceding claims 1-3 for assembling a down-the-hole drilling apparatus, wherein the drill head of the drill unit (3) of the drilling device consists of a first body part (4a) and a second body part (5a) , wherein the drilling elements of the first and second drilling elements (4, 5) , such as a unitary cutting part, separate bits, inserts or the like, are arranged on the drilling faces (P; Pl, P2) formed by the end faces of said body parts (4a, 5a) , characterized in that the fastening arrangement (xl, x2) is formed by machining on the surface of the sleeve part (z) one or more features such as a toothing, for instance a pyramid-shaped or otherwise triangular cross-sectioned toothing, a straight and / or conical toothing, a groove, a shoulder, a thread formed in the longitudinal direction (s) , such as a straight or conical machine-, flat-, or trapezoidal thread and / or the like, a ridge, a rough friction surface, a form lock and / or the like.

5. A method according to any of the preceding claims 1-4, characterized in that the plastic pipe (2) used is an essentially unprocessed raw pipe blank, which is preferably made, for example, of plastic, such as PE, PEH-, PVC-plastic or the like, and / or of a reinforced plastic material, such as fiber-reinforced plastic or the like.

6. A method according to any of the preceding claims 1-5, characterized in that the sleeve part (z) provided with the fastening arrangement (xl, x2) is arranged integrally with the end (II) opposite the drilling face of the first drilling elements (4) , the second drilling elements (5) or the casing shoe (8) .. A method according to any of the preceding claims 1-6, characterized in that the external tool (7) is a radial press (7b) or a bushing.

8. A method according to any of the preceding claims 1-6, characterized in that the internal tool (6) is a conical mandrel or an expandable mandrel.

9. A down-the-hole drilling apparatus, in which there is a drilling device for performing drilling using a plastic pipe with a drill unit (3) , which comprises a drilling arrangement at its drill head, such as first drilling elements (4) for drilling a central hole and second drilling elements (5) for reaming the central hole for the plastic pipe (2) , wherein the drilling elements (4, 5) are connected to each other at least in a drilling situation to transmit force for their joint rotational, feed and / or percussion movement, and detachably connected to the plastic pipe (2) to enable the removal of at least the first drilling elements(4) from the drilled hole, wherein the plastic pipe (2) is arranged to be pulled into the drilled hole by a force effect, which is applied to it from the drill unit (3) , such as from the second drilling elements (5) or from a casing shoe (8) connected to them to transmit force at least in the longitudinal direction (s) of the drilling device, characterized in that the drill unit (3) and the plastic pipe (2) are connected to each other by a sleeve part (z) of a drilling arrangement, such as the second drilling elements(5) or the casing shoe (8) , at an end (II) opposite the drilling face (P) of the drill unit (3) , said sleeve part (z) having a radial (r) fastening arrangement (xl, x2) , wherein the plastic pipe (2) is fastened by physically treating to the sleeve part (z) in the radial direction (r) , such that an immovable contact surface (KI, K2 ) is formedbetween the surface of the end (I) of the plastic pipe and the sleeve part (z) of the casing shoe (8) in the longitudinal direction (s) for pulling the plastic pipe (2) into the drilled hole by the force effect transmitted from the casing shoe (8) .

10. A down-the-hole drilling apparatus according to claim 9, characterized in that the sleeve part (z) of the casing shoe (8) comprises an internal fastening arrangement (xl) , wherein the mutual contact surface (KI) between the internal fastening arrangement (xl) and the end (I) of the plastic pipe (2) is formed such that the end (I) of the plastic pipe (2) is arranged in the radial direction (r) inside the sleeve part (z) provided with the fastening arrangement (xl) , and wherein the end (I) of the plastic pipe (2) is expanded from its internal space in the radial direction (r) against at least the fastening arrangement (xl) of the sleeve part (z) , such that the fastening arrangement (xl) is fastened to the outer surface of the end (I) of the plastic pipe (2) , at least partially pressing into it.

11. A down-the-hole drilling apparatus according to claim 9, characterized in that the sleeve part (z) of the casing shoe (8) comprises an external fastening arrangement (x2) , wherein the mutual contact surface (K2) between the external fastening arrangement (x2) and the end (I) of the plastic pipe (2) is formed such that the end (I) of the plastic pipe (2) is arranged in the radial direction (r) outside the sleeve part (z) provided with the fastening arrangement (x2) , and wherein the end (I) of the plastic pipe (2) is compressed in the radial direction (r) against the fastening arrangement (x2) direction of the sleeve part (z) , such that the fastening arrangement (x2) is fastened tothe inner surface of the end (I) of the plastic pipe (2) , at least partially pressing into it.

12. A down-the-hole drilling apparatus according to any of the preceding claims 9-11, wherein the drill head of the drill unit (3) of the drilling device consists of a first body part (4a) and a second body part (5a) , the drilling elements of the first and second drilling elements (4, 5) , such as a unitary cutting part, separate bits, inserts or the like being arranged on the drilling faces (P; Pl, P2) formed by the end faces of said body parts, characterized in that the fastening arrangement (xl, x2) formed on the surface of the sleeve part (z) comprises one or more features such as a toothing, such as a pyramid-shaped or otherwise triangular cross-sectioned toothing, a straight and / or conical toothing, a groove, a shoulder, a thread formed in the longitudinal direction (s) , such as a straight or conical machine-, flat-, or trapezoidal thread and / or the like, a ridge, a rough friction surface, a form lock and / or the like.

13. A down-the-hole drilling apparatus according to any of the preceding claims 9-12, characterized in that the fastening arrangement (xl, x2) on the sleeve part (z) of the casing shoe (8) is formed in a pre-fabrication stage, before the casing shoe (8) and the plastic pipe (2) are connected to each other.

14. A down-the-hole drilling apparatus according to any of the preceding claims 9-13, characterized in that the sleeve part (z) provided with the fastening arrangement (xl, x2) is arranged integrally with the casing shoe (8) .

15. A down-the-hole drilling apparatus according to any of the preceding claims 9-14, characterized in that theplastic pipe (2) used in the drilling is an essentially unprocessed raw pipe blank, which is advantageously made, for example, of plastic, such as PE, PEH-, PVC-plastic or the like, and / or of a reinforced plastic material, such as fiber-reinforced plastic or the like.

Images