A device, system and method for extraction of a drill core from a material

Abstract

A device for extraction of a drill core (1) from a material, comprising: a borer (2) having a longitudinally extending cylindrical shaft (3) with a first end and a second end and with a cutting thread (4) at the first end, wherein a cylindrical hollow space (6) is formed in the shaft (3), wherein the hollow space (6) extends through the whole shaft (3) from the first end to the second end and comprises a first opening (7) at the first end in a center of the cutting thread (4) and a second opening (8) at the second end and wherein the borer (2) is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core (1 ) through the first opening (7) within the hollow space (6) during drilling, is characterized in that an inner diameter of the hollow space (6) expands beginning from a foremost cutting edge (5) of the cutting thread (4) at the first end in direction to the second end up to a defined distance, thereby forming an expanding inner surface (10). Further, a corresponding system for extraction of a drill core (1) from a material comprises such a device and a handle or a driving unit for driving the borer (2). Further, a corresponding method for extraction of a drill core (1) from a material comprises the following steps: inserting a drill core (1) receiving tube (11) in the hollow space (6) through the second opening (8); drilling the borer (2) into the material in a forward direction with the first end ahead; receiving at least a part of the drill core (1) through the first opening (7) within the hollow space (6) during drilling; and removing the tube (11) with the part of the drill core (1) or with the drill core (1) in the tube (11).

Description

[0001] A DEVICE, SYSTEM AND METHOD FOR EXTRACTION OF A DRILL CORE FROM A MATERIAL

[0002] The present invention relates to a device for extraction of a drill core from a material, comprising: a borer having a longitudinally extending cylindrical shaft with a first end and a second end and with a cutting thread at the first end, wherein a cylindrical hollow space is formed in the shaft, wherein the hollow space extends through the whole shaft from the first end to the second end and comprises a first opening at the first end in a center of the cutting thread and a second opening at the second end and wherein the borer is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core through the first opening within the hollow space during drilling.

[0003] Further, the present invention relates to a system for extraction of a drill core from a material, comprising: a device as mentioned above and a handle or a driving unit for driving the borer.

[0004] Further, the present invention relates to a method for extraction of a drill core from a material, particularly by means of a device or system as mentioned above, wherein the device comprises: a borer having a longitudinally extending cylindrical shaft with a first end and a second end and with a cutting thread at the first end, wherein a cylindrical hollow space is formed in the shaft, wherein the hollow space extends through the whole shaft from the first end to the second end and comprises a first opening at the first end in a center of the cutting thread and a second opening at the second end and wherein the borer is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core through the first opening within the hollow space during drilling.

[0005] In the 1860s, the forester Max Robert Pressler described a construction he had invented for taking cylindrical wood samples from trees in a patent application. He called it the "increment borer" because it could be used to assess the annual radial increment of trees based on the growth rings, comprising the soft earlywood and the mostly darker, denser latewood. Since then, increment borers have been used thousands of times worldwide to take "drill cores" from trees and timber. The "extracted" samples are either examined immediately on site for wood quality, discoloration, decay and growth, and / or subsequently prepared in the laboratory in order to measure cell or growth ring structures under a microscope, for example. A description of this technology and how to use it can be found, for example, in the following documents:

[0006] Maeglin, R. R. (1979): Increment Cores: How to Collect, Handle, and Use Them. (Vol. 25). US Department of Agriculture, Forest Service, Forest Products Laboratory, Madison Wl.

[0007] Agee, James K. & Mark H. Huff (1986): The care and feeding of increment borers. Seattle, WA: National Park Service. 15 p.

[0008] Jozsa, Les (1988): Increment core sampling techniques for high quality cores. FORINTEC Canada.

[0009] Special Publication N. SP-30. ISSN #0824-2199.

[0010] Forster, T., Schweingruber, F. H., & Denneler, B. (2000): Increment puncher. A tool for extracting small cores of wood and bark from living trees. IAWA Journal, 21 (2), 169-180.

[0011] Grissino-Mayer, H. D. (2003): A manual and tutorial for the proper use of an increment borer. Tree-Ring Research. 59 (2), 63-79 (2003).

[0012] Caetano-Andrade, V. L., Jochen Schdngart, Wellyngton Espindola Ayala, Ramiro Dario Melinski, Francisco Silva, Reinhard Dobrindt & Patrick Roberts (2021 ): Advances in increment coring system for large tropical trees with high wood densities. Dendrochronologia. 68, 125860 (2021 ).

[0013] Any significant changes in local growth conditions, stand dynamics, air- and soilpollution, local weather and climate have a specific impact on number, size and properties of the annually newly built wood cells by the cambium (between bark and stem). In consequence, trees are continuously reflecting and “storing” detailed information on any important environmental factors in form of specific structural properties (“traits”). Detailed scientific analysis showed that tree-rings are the most important (because most “honest” and detailed) global natural archive on variations in climate (temperature, precipitation, wind, etc.) and environmental factors (air pollution, soil erosion, soil compaction, use of agricultural fertilizers, pesticides and fungicides, etc.) since the last ice age. This is why thousands of research institutes world wide are taking increment cores from many trees for subsequently measuring tree-ring and wood cell properties. Fundamental data and conclusions in environmental and climate research are based on the analysis of tens of thousands of such drill cores from often old or very old trees and (archaeological) wood samples from all over the world.

[0014] Pressler’s increment borers are also used daily by the thousands in quality control of forest plantations as well as in natural forests around the world. When forest owners want to sell wood / timber on the world market successfully, for example, they first need to obtain a corresponding label, proving that their forest management fulfills the conditions of sustainability. For this, they need to prove that they do not harvest more wood volume from a forest than is annually growing in the respective area. As part of this “sustainability-check” procedure, it is necessary to determine the past growth rates, preferably done by taking increment cores. Based on the analysis of the drill cores, it is then possible to estimate the annual timber volume growth of the forest in question. Based on this information, the maximum number of trees can be determined that are allowed to be harvested for forestry purposes by still fulfilling the conditions of the corresponding sustainability label.

[0015] In addition, there are many other applications in forestry and environmental research and consultancy, where it is necessary to study the past growth of trees without cutting them down. So, taking increment cores is a standard procedure in these markets worldwide and happens daily.

[0016] Most increment borers have a length of approx. 40cm and deliver a drill core with a diameter of approx. 5mm from a drilling hole of approximately 12mm.

[0017] Special sizes of increment borers go up to 1 meter deep into the tree, but then with thicker cores of 12mm or 15mm and borehole diameters of up to 20mm and more. In order to minimize damage to the sampled trees and timbers, the drill hole diameters have so far mostly been kept under 13mm. Significantly thicker increment borers are only tolerated in rare special cases because they lead to correspondingly bigger damage to the tree or timber.

[0018] The logical consequence of the thin diameters is a corresponding mechanical fragility of the cylindrical wood samples, i.e. the usually only approx. 5mm thin and yet long (often 400mm) drill cores. This fragility of the samples, due to their geometry alone, requires appropriate care during sampling and further handling, which results in correspondingly higher amount of work and costs.

[0019] Most increment borers are still operated and driven manually. Since the advent of battery powered cordless drills, these are also sometimes used. However, as sampling, particularly for climate and environmental research, often takes place over days in the field, in all weather conditions, in the mountains and at tree borders, vehicles often cannot be taken to the tree. The use of electric (or even gasoline driven) tools is therefore naturally limited. And that's why most increment borers are still inserted manually into trees and wood. In addition, there is yet no portable electric drill with sufficient torque that is required to turn the current kind of increment borers deep enough into hardwood species trees.

[0020] Although many companies manufactured increment borers and tried to optimize these tools since their original invention about 160 years ago, fundamental technical problems still occur today, not only making the practical use of increment borers often difficult and burdensome but furthermore sometimes making it impossible to take the desired or required samples.

[0021] Depending on the tree species and manufacturer of the increment borer, many or even most of the cores are twisted, show cracks or even break through during sampling or afterwards, which makes further processing correspondingly more difficult - not only because the sequence and orientation of the fragments must remain correct, but also, because the cell and growth ring properties in the fragments should always be measured at the same fiber angle, especially under the microscope. Cracks (and subsequent breakages) often occur due to an "unfavorable" internal geometry of the common increment borers at the front cutting edge: the internal diameter is constant there (depending on the manufacturer) over a distance of a few millimeters to more than one centimeter. This results in strong friction on the core wood along this distance, which leads to a considerable torque on and torsion of the drill core. In view of its small diameter (usually approx. 5 mm), cracks quickly form in the drill core or even breakage occurs due to this torsion while drilling. This is of course also due to the fact that torsional strength of wood (as an extremely anisotropic material) is lower by factors than, for example, the compressive and tensile strengths. The easiest way to break a tree-stem or any piece of wood is by torsional loading.

[0022] In some increment borers or core sampling tools, the inner diameter even decreases behind the front cutting edge (see for example: Foster et al. 2000), strongly squeezing the wood sample and systematically creating cracks, deformations and other damages.

[0023] The torsion to the drill core during the sampling process is not only and not simply due of the fact that the inner diameter of the increment borers is constant at the tip for a certain distance. There is another reason for increased friction in this section of the increment borer: wood immediately expands as soon as it is cut out of a tree. In the tree, wood is constantly squeezed by the vertical pressure (due to the weight of the above mass: stem and crown) and by a tangential (=circumferential) compression stress (due to several structural properties and moisture content). In consequence: when the core is cut out of its surrounding woody neighborhood in the stem, it immediately expands, increasing the friction inside the increment borer (in the area where the inner diameter stays constant). This friction leads to more twisting of the wood of the drill core and thus makes cracks more probable and further analysis more difficult.

[0024] Twisted fibers, cracks and, in particular, fractures make subsequent analysis of the drill cores considerably more time-consuming or sometimes even almost impossible, not only under the microscope, but often already on site. As a result, often only a few of the cores taken can be finally used for measurements and further analysis, which in turn means that mostly additional cores have to be taken on site either as a preventative measure or after unsuccessful attempts on the same tree. This in turn leads to correspondingly more work and greater damage to the trees - because not only is there usually a subsequent discoloration of the wood around the drill channel (due to oxidation, among other things), but a new fungal infection can also occur, or decay already present in the tree can spread more quickly through the bore hole. This is another reason why it makes sense and is necessary to take as few cores as possible (apart from effort and efficiency). However, this would only be possible if there would be a good chance to reliably take cores of sufficiently good quality (no cracks, no breaks, no squeezing, no twisting, etc.), which has not been the case to date.

[0025] The torsion at the increment borer cutting edge not only often leads to cracks or even fractures in the drill core, but also often causes the fiber angle to change along the respective drill core (because the wood in the drill core is twisted during drilling): while the wood fibers are vertical at the front (necessary for the vast majority of microscopic examinations and measurements), they can be twisted by 45° or even 90° at the other end of the drill core. This makes it almost impossible to analyze cells and growth rings, as the corresponding measurements must always be carried out at the same angle referring the (vertical) cell axis. To measure cells and growth rings correctly, for example, you usually have to look "from above" onto or into the wood cells (tracheids and vessels) in always the same angle. Twisted cores make it difficult or even impossible to do so.

[0026] Once the desired or maximum penetration depth has been reached with the increment borer on the tree or timber, the question then always arises as to when and how the drilled core is best removed from the increment borer. Unfortunately, there is yet no single best solution here, but rather different concepts with advantages and disadvantages depending on the type of tree, condition and moisture content of the wood: it is often recommended to insert the so-called “extractor” from behind when the maximum drilling depth is reached. Then turn the increment borer back by a full turn in order to release the core from the wood body. Then pull the core out of the increment borer with the help of the “extractor”. The "extractor” is effectively a very long, thin "steel spoon" (= typically a ~50° ring segment with several backward oriented barbs at the front) or half circular metal tray, which is inserted along the drill core from behind into the increment borer in order to then pull out the drill core from the back.

[0027] One problem in this context comes from the fact that the drill cores are usually twisted and deformed (also due to the above-mentioned torsion and the deformation) and not straight, touching the inner wall of the increment borer at many places. When the extractor is then inserted from the back, the increment core is usually damaged. The same happens when the increment core is then pulled out with the help of the extractor (hooked at the core with the help of the barbs). Removing the drill cores with the extractor should therefore theoretically be avoided as far as possible - but is often the only solution to date because, mostly, the drill core cannot be removed from the increment borer in any other way (without damaging or even destroying it).

[0028] If, alternatively, the increment borer is removed from the tree or timber with the drill core still in it, this has again disadvantages. The time for drilling out creates additional problems: the (usually moist) wood of the drill core is stronger deformed during this time (due to heating of the shaft by friction) and becomes increasingly wedged in the increment borer, or even glued to the inner surface (due to sticky raisin in the wood). One of the reasons for this is that moisture inevitably evaporates due to the heat generated during drilling, which immediately leads to a corresponding deformation of the wood. Descending moisture content is one of the major reasons why beams or boards deform after being sawn.

[0029] It is therefore often impossible to remove the drill core from the increment borer without damage, deformation or cracks I fractures, which makes all subsequent work steps more difficult or even impossible - apart from the fact that this often means that many more cores have to be taken than are actually necessary (which causes more work and more damage to the trees).

[0030] The geometry of the cutting edge of conventional increment borers is designed in such a way that it is difficult or even impossible to remove them from the tree or timber as soon as the cutting edge enters an internal cavity or decay in the tree or when the tip had reached the end of the local diameter and thus passed the local sample diameter. The problem in re-pulling the increment borer is (depending on the manufacturer’s design of the increment borer) mainly due to the fact that the cutting edge of the increment borer drops off abruptly at the back or that there is even a cam at the rear end of the cutting edge to widen the drill channel while drilling in. This often leads to such increment borers getting stuck in trees or timber because they can no longer be pulled out with the technical aids available on site.

[0031] In the case of standing trees, the wood of the tree expands quickly around the drill channel anyway, thus narrowing the bore hole, making it even more difficult to pull the borer back. A higher torque must therefore often be applied when unscrewing the increment borer compared to when drilling in.

[0032] If the cutting edges at the threaded tip of the increment borer are stuck in a cavity or decay, it is often difficult or even impossible to turn back or pull the increment borer out due to the steeply rising cutting edge or the aforementioned cam without destroying the borer.

[0033] As a result, many increment borers or their tips are still stuck in trees around the world, which not only damages the tree, but also leads to corresponding damage in the sawmill during subsequent forestry utilization of the corresponding tree.

[0034] Due to the aforementioned boundary conditions, most increment borers are driven manually. The cutting threads of the increment borers developed for this manual handling usually have a pitch of approx. 4 to 5mm. Two-edged threads tend to be used for high-density tree species and three-edged threads for "normal" woods.

[0035] The density of the strongest wood species go up to approximately 1300kg / m3. The lowest densities of some wood species are found around 100 to 200 kg / m3. Thus, there is a big spread in the material property that strongly determines the resistance while drilling in. Unfortunately, there are currently very few cordless electric drilling machines with a sufficiently high torque to be able to turn these increment borers in trees at all. Even the most powerful cordless electric drills currently available are not yet able to extract core samples from many hardwood species with wood density above 1000kg / m3- mainly because the cutting thread pitch (and therefore the feed rate) is too high for this, causing correspondingly too high torque.

[0036] The few increment borer types specially developed for motorized sampling therefore have cutting thread pitches of typically around 1 mm. This lowers the torque required to rotate the increment borer, but increases the number of required turns correspondingly. This extents the time required for drilling and increases the heat created by the drilling with all its negative effects, mentioned above. For example, then more resin comes out of the drill core, gluing it even stronger to the inner side of the increment borer, making it often impossible to extract the drill core without destroying it.

[0037] Using borers with that low pitch of only 1 mm allows to take core samples from many tree species with battery driven cordless drills, because required torque is much lower. But, if such increment borers have to be used manually (due to a lack of power supply I empty battery), sampling is very laborious and time-consuming due to the correspondingly lower feed rate. And, more heat is created in the drill core due to the much longer time of drilling (with all its negative effects).

[0038] So, for being flexible, different kinds of increment borers and tools have to be carried to the trees what is burdensome especially when having to hike through forests and / or mountains for getting to the desired trees.

[0039] Depending on the type of wood, the drill cores contain different amounts of resins and other (liquid) wood constituents, coming out of the drill core during drilling and gluing the wood in the increment borer shaft. This effect is getting stronger by the heat created during drilling, especially by the friction at the front of the increment borer. This not only leads to considerable contamination of the increment borer but, furthermore, sometimes the drill cores even stick to the increment borer and can hardly be removed without being damaged or destroyed. Therefore, increment borers must always be cleaned after sampling (e.g. with spirit), which not only takes time, but also means that additional equipment must be carried.

[0040] If the drill core is not removed from the increment borer immediately at the maximum or intended deepest point of the bore hole, but only after the borer has been completely drilled back, then it is quite possible that the drill core has become so firmly stuck or even glued to the inner walls of the shaft in the increment borer in the meantime that it is almost impossible to get it out without breaking or completely destroying it.

[0041] In many applications, the extracted drill cores are bound on wooden strips, placed in plastic web plates or wrapped in paper directly after removal from the increment borer. However, the drill cores are usually not straight, but more or less bent and deformed (by the sampling process), often kinked or even broken. This is why it is sometimes difficult or even impossible to insert the drill cores into storage containers without damaging them due to their fragility (or mixing the sequence, direction I angle of the parts). This process also regularly results in (additional) damage to the drill cores, which often even leads to the loss of the samples or to their inability to be measured. As a result, additional cores usually have to be taken or the sampling efforts have been for nothing.

[0042] Most wood cores are taken to analyze wood quality (intact / decayed), wood strength, or growth properties. The growth analysis usually includes the measurement of the (radial) width of the growth rings, often even the (radial) width of earlywood and latewood. Sometimes, in addition, wood density is measured by means of x-ray through-beam or high-frequency reflectance machines because the radial density profiles covers even more information about wood quality, tree-growth, environmental factors influencing the growth of wood cells than just the measured sizes (width of earlywood and latewood).

[0043] The earlywood is formed at the beginning of the annual vegetation period, mainly from stored reserves from the previous growth season, followed by the latewood until the end of the growth period (typically April to September in boreal forests of the northern Hemisphere, depending on the weather also earlier / later, longer or shorter). For these measurements, the drill core surface is either cut by hand or with a microtome, or sanded (with sandpaper grits up to 10,000). For this purpose, the drill cores must of course be mounted and fixed appropriately, otherwise they would break again due to the mechanical stress and would then be difficult or even impossible to measure under the microscope. Handling the fragile and, unfortunately, so far mostly deformed, kinked or broken drill cores is correspondingly time-consuming and yet error-prone. As a result, samples are regularly lost during further work steps in the laboratory - another reason why many more cores are usually taken than are actually needed and measured afterwards, which causes more damage to the sampled trees and woods and means more work.

[0044] Unfortunately, gluing the drill cores to a wooden support is only a theoretical option. On the one hand, it is difficult to fix the drill cores perfectly, which usually consist of fragments, in the correct position in relation to each other and at the same fiber angle, which is optimal for the later measurements. Secondly, after gluing, it is no longer possible to examine and measure the wood of the drill core at other angles for other purposes. Finally, it must unfortunately be noted that wood-glue and other adhesives inevitably penetrate the wood and change it chemically, which makes subsequent material analyses of the wood virtually impossible. For this reason, most laboratories avoid gluing the drill cores and therefore have difficulties in not damaging the drill cores even further during the analysis and measurement steps, despite the great effort involved, because they are so fragile.

[0045] In summary, for the above-mentioned reasons, drill cores are often damaged during and / or after the coring process, cannot be removed undamaged from trees or timber and frequently cannot be correctly assessed or properly measured. For this reason, many more drill cores often have to be taken in order to have at least a few to work with in the end (leading to low efficiency and more damage to the sampled trees).

[0046] In this context, it is quite legitimate to ask why, in over 150 years of use and further development of "increment borers", the fundamental problems described here have not yet been solved. It is an objective of the present invention to improve and further develop a device, system and method for extraction of a drill core from a material for providing an efficient and safe extraction of a drill core from a material by simple means.

[0047] This objective is addressed by the subject-matter of the independent claims.

[0048] In accordance with the invention, the aforementioned objective is accomplished by a device according to claim 1 . The device is characterized in that an inner diameter of the hollow space expands beginning from a foremost cutting edge of the cutting thread at the first end in direction to the second end up to a defined distance, thereby forming an expanding inner surface.

[0049] Further, the aforementioned objective is accomplished by a system for extraction of a drill core from a material according to claim 14, wherein the system comprises a device according to one of claims 1 to 13 and a handle or a driving unit for driving the borer.

[0050] According to the invention it has been recognized that it is possible to provide a very efficient and safe extraction of a drill core from a material by a special design of the hollow space. Concretely, it has been further recognized that providing a hollow space with an expanding inner diameter beginning from a foremost cutting edge of the cutting thread at the first end enables a safe guiding of a usually fragile drill core into the hollow space. The expanding inner diameter ensures that the drill core does not undergo any friction and torsion in the borer during the drilling process and that no additional heat and damage is generated. This prevents the formation of cracks, fractures and deformations of the drill core. The hollow space expands in direction to the second end up to a defined distance in the hollow space, thereby forming an expanding inner surface of the hollow space. Due to the fact that the drill core can be safely guided into the hollow space by the provided device, it is not necessary to produce a great number of drill cores for getting at least some nearly undamaged drill cores. Thus, the number of drill cores necessary for suitable analysis results can be reduced by the application of the device and borer according to the invention. Thus, based on the invention, an efficient and safe extraction of a drill core from a material by simple means is possible.

[0051] According to an embodiment the device can comprise a drill core receiving tube which can be inserted in the hollow space through the second opening. Such a tube is provided for reliably and efficiently obtaining an intact drill core immediately after being guided through the first end of the shaft and along the expanding inner surface. Contrary to the spoon-like extractor of the prior art, a drill core can be safely collected within the circumferentially closed tube of this embodiment. Further, a safe handling, transport and storing of collected drill cores is possible in such a tube.

[0052] Prior to the use of the device, the tube is inserted into the hollow space through the second opening. Then the borer is drilled into the material. According to a further embodiment a radially extending stop, shoulder or stop surface for the tube can be formed in the hollow space. Such a stop, shoulder or stop surface limits the inserting depth of the tube into the hollow space and provides a suitable positioning of the tube in the hollow space.

[0053] According to a further embodiment the radially extending stop, shoulder of stop surface can be formed at an inner end of the expanding inner surface, preferably directly at the defined distance, where the expanding inner surface ends. Thus, the tube can be inserted into the hollow space up to the inner end of the expanding inner surface and therefore a drill core can be received within the tube immediately after having passed the expanding inner surface during the drilling process.

[0054] In a further embodiment the stop surface can form an annulus wherein an inner diameter of the annulus can be larger than the inner diameter of the hollow space at the foremost cutting edge of the cutting thread. Such an annulus or ring surface provides a reliable stop for the tube during its insertion in the hollow space without damaging a drill core coming in the hollow space from the first end of the shaft.

[0055] According to a further embodiment an inner diameter of the tube can be larger or equal than the inner diameter of the annulus. This provides a safe passing of the annulus by the drill core during its way into the tube during the drilling process. Thus, the drill core can enter the tube without any blocking step or interruption.

[0056] In a further embodiment the tube can be longer than the shaft or longer than the distance between the stop, shoulder or stop surface and the second end. Thus, in the inserted position, the tube projects outwardly from the second end of the shaft and can be easily gripped and pulled out from the second end. This provides a simple handling of the device.

[0057] According to a further embodiment the tube can be at least partially transparent or at least partially made from a transparent material. This enables a simple visual inspection of the collected drill core only by view from outside.

[0058] Within a further embodiment the tube can be at least partially flexible or at least partially made from a flexible material. This enables a mechanical test of the drill core by applying a slight pressure on the tube with fingers, for example.

[0059] According to a further embodiment the cutting thread can have a radially extending circumferential protrusion, wherein the protrusion can radially extend beyond an outer diameter of the shaft. Such a protrusion ensures that a drill channel within the material expands sufficiently during penetration and that a shaft friction is minimized during the drilling process. In summary, a simple and easy operation of the device can be guaranteed. Such a protrusion can also be denoted as a hump, which exceeds an outer diameter of the shaft.

[0060] In a further embodiment at least a portion of the cutting thread can be designed for cutting in a backward direction. This enables a cutting from behind resulting in an easy and efficient pulling back of the borer into a backward direction out of the material.

[0061] According to a further embodiment at least a part of the portion can have an increasing diameter beginning at a rear end of the cutting thread in direction to the first end. This feature is very helpful for ensuring a safe and easy removal of the increment borer from materials like trees even when the complete cutting thread is in an inner cavity or in a decay, or if the cutting thread has reached the other side of the local diameter, where the cutting thread has exited the probed sample on an opposite side.

[0062] The kind of material is not limited, as long the borer can be drilled into the material. According to various embodiments the material can be a wooden substance, a soil, snow or ice, for example.

[0063] Further, the aforementioned object is accomplished by a method for extraction of a drill core from a material according to claim 15, particularly by means of a device according to one of claims 1 to 13 or by a system according to claim 14, wherein the method is characterized by the following steps:

[0064] - inserting a drill core receiving tube in the hollow space through the second opening;

[0065] - drilling the borer into the material in a forward direction with the first end ahead;

[0066] - receiving at least a part of the drill core through the first opening within the hollow space during drilling; and

[0067] - removing the tube with the part of the drill core or with the drill core in the tube.

[0068] Contrary to prior art methods a drill core receiving tube is inserted in the hollow space through the second opening at the beginning of the method. Then the borer is drilled into the material in a forward direction with the first end ahead and with the tube in its hollow space. During the drilling at least a part of the drill core is safely received through the first opening within the hollow space. As a last step the tube is removed from the hollow space for further handling of the tube with the part of the drill core or with the drill core in the tube. This removing step can be performed with the borer still drilled in the material or with the core already removed out of the material.

[0069] The present disclosure provides a new device, system and method for damage-free extraction, transport, preparation, analysis and / or storing of drill cores. There are several ways how to design and further develop the teaching of the present invention in an advantageous way. To this end, it is to be referred to the dependent claims on the one hand and to the following explanation of preferred embodiments of the invention by way of example, illustrated by the figure on the other hand. In connection with the explanation of the preferred embodiments of the invention by the aid of the figure, generally preferred embodiments and further developments of the teaching will be explained. In the drawing

[0070] Fig. 1 shows in a schematical longitudinal section a front part of an embodiment of a device according to the present invention, wherein the first end of the borer with the cutting thread is shown, and

[0071] Fig. 2 shows in a cross-section the device according to Fig. 1 .

[0072] Throughout the present disclosure, like reference numbers denote like or at least substantially similar elements.

[0073] In Fig. 1 is shown a front part of an embodiment of a device for extraction of a drill core 1 from a material according to the present invention. The device comprises a borer 2 having a longitudinally extending cylindrical shaft 3 with a first end and a second end and with a cutting thread 4 at the first end. The cutting thread 4 comprises a foremost cutting edge 5 at the first end. A cylindrical hollow space 6 is formed in the shaft, wherein the hollow space 6 extends through the whole shaft 3 from the first end to the second end and comprises a first opening 7 at the first end in a center of the cutting thread 4 and a second opening 8 at the second end. The borer 2 is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core 1 through the first opening 7 within the hollow space 6 during drilling.

[0074] For providing an efficient and safe extraction of a drill core 1 from a material by simple means an inner diameter 9 of the hollow space 6 expands beginning from the foremost cutting edge 5 of the cutting thread 4 at the first end in direction to the second end up to a defined distance, thereby forming an expanding diameter of the inner surface 10. The device comprises a drill core receiving tube 11 inserted in the hollow space 6 through the second opening 8. An insertion of the tube 11 into the hollow space 6 is limited by a radially extending stop surface 12 which is formed in the hollow space at an inner end 13 of the expanding diameter of the inner surface 10. Specifically, the stop surface 12 forms an annulus wherein an inner diameter of the annulus is larger than the inner diameter of the hollow space 6 at the foremost cutting edge 5 of the cutting thread 4. An inner diameter of the tube 1 1 is larger or equal than the inner diameter of the annulus and the tube 11 can be longer than the distance between the stop surface 12 and the second end. Thus, the tube 11 can easily be pulled out of the hollow space 6.

[0075] Further, the tube 11 is made from a transparent material for providing a possibility of a visual inspection of the drill core 1 in the tube 11 .

[0076] The cutting thread 4 has a radially extending circumferential protrusion 15, wherein the protrusion 15 radially extends beyond an outer diameter of the shaft 3. A portion 16 of the cutting thread 4 is designed for cutting in a backward direction for simplifying a removal of the borer 2 out of the material. Specifically, at least a part of the portion 16 has an increasing diameter beginning at a rear end 17 of the cutting thread 4 in direction to the first end.

[0077] The material can be a wooden substance, a soil, snow or ice, for example.

[0078] Fig. 2 shows in a cross-section the device according to Fig. 1 with the drill core 1 in the center. The tube 11 is partially inserted - up to the stop surface 12 - in the hollow space 6 of the shaft 3 of the borer 2.

[0079] In order to guide the fragile thin wooden drill core 1 safely into the shaft 3 of the increment borer 2 as undamaged as possible during drilling, the inner diameter of the borer 2 must expand immediately after the foremost cutting edge 5. This ensures that the drill core 1 does not undergo any further friction and torsion in the increment borer 2 during the drilling process and that no additional heat and damage is generated. This prevents the formation of cracks, fractures and deformations. The escape of adhesive wood constituents is also minimized.

[0080] However, this change in the inner geometry of the borer 2 is only one of two important changes of the concept of increment boring for reliably and efficiently obtaining intact drill core samples. In addition, the fragile wooden core has to be collected safely in a special way, that prevents further damage and deformation, not only during the sampling process (the coring) but furthermore for transporting, further processing the drill core samples and storing. This is achieved with a for example thin-walled, straw-like tube 11 that is inserted into the clean and empty increment borer 2 from behind before drilling. This tube 11 is pushed in up to a shoulder, stop or stop surface 12 inside the increment borer shaft 3. This tube 11 should preferably be longer than the increment borer 2 so that it can be easily pulled out again at the back or second opening 8.

[0081] Wall thickness and diameter of the tube 11 are selected so that it fits well into the shaft 3 and also has a sufficient internal diameter 14 to accommodate the drill core

[0082] 1 without significant friction. The inner edge of the tube 11 must never be inside the inner edge of the stop shoulder or stop surface 12, so that the drill core 1 can enter the tube 11 without any blocking step or interruption.

[0083] For taking increment cores or drill cores 1 with a diameter of approx. 5mm out of trees, it seems preferable to use a tube 11 with an outer diameter of 6mm and a wall thickness of approx. 2 / 10mm.

[0084] The tube 11 is therefore first used to pick up the drill core 1 with as little damage as possible during the drilling process, then to remove it from the increment borer 2 without creating any further defects, and then to visually inspect, transport, store, further process and analyze the sample.

[0085] An automatic and additional advantage of this design is that the increment borer bit

[0086] 2 does not get dirty and sticky inside because the drill core 1 only enters the receiving tube 11 and does not touch the shaft 3 internally (except for the cutting front edge 5). Due to the expansion of the inner diameter directly behind the front cutting edge 5, the heating of the cylindrical wood sample (by friction) is significantly lower than was previously the case (for 150 years of use of the increment bore technology). As a result, there is not only correspondingly less friction, but less temperature mobilization of resin, adhesive and other wood constituents and also less deformation of the sample - apart from the fact that this prevents cracks, fractures, twisting and other damages.

[0087] If the drill core 1 is preferably already pulled out of the drill bit by means of the tube 11 when the increment borer 2 has reached the maximum or desired penetration depth, this has several further advantages at the same time: in particular, the drill core 1 can then no longer be damaged when the increment borer 2 is unscrewed manually or by means of an electric tool, but can rather be brought "to safety" and analysis immediately.

[0088] To ensure that the drill channel within the probed tree or timber expands sufficiently during penetration and that shaft friction is minimized during the drilling process, the base line of the threads has a "hump" or protrusion 15, exceeding the diameter of the shaft 3 significantly, by at least 30%, for example, in order to push the surrounding wood outwards accordingly and minimize shaft friction in the tree or timber.

[0089] For pulling back the increment borer 2 efficiently by turning into the opposite direction, the tip cutting thread 4 must also cut from behind and increase in diameter at a portion 16. This way, the tip can also turn into the material when the cutting thread 4 comes back out of a cavity or decay on the way back from the wood or material body. This is important for ensuring a safe and easy removal of the increment borer 2 from trees and timber even when the complete cutting edge 4 is in an (inner) cavity or in a decay, or if the borer tip has reached the other side of the local diameter, thus the tip cutting thread 4 has exited the probed sample on the opposite side. The combination of geometrically expanding cutting thread 4 or thread base (the “hump” or protrusion 15) and backward-cutting drill cutting edges at portion 16 makes it easier to unscrew the increment borer 2 because friction is then significantly reduced. In addition, this prevents damages and losses of increment borers 2 as common to date, reducing the number of necessary drillings and thus the damage to the corresponding tree. And, it prevents increment borers 2 from getting stuck and left in trees.

[0090] If the tube 11 is made of transparent flexible plastic, for example cellulose acetate or PLA, it is not only possible to visually assess the color, consistency and quality of the drill core 1 immediately, but also to test it mechanically by applying slight pressure (with fingers, for example). If the wood is decayed, this is mostly visible by discoloration, but not always. In addition, the amount of discoloration is not linearly correlated to the degree or deterioration. This is why it is advantageous when the tube 11 allows to apply a bit of pressure for testing wood quality of the core without damaging it. If the wood of the drill core 1 is intact, it is usually impossible to squeeze it. If it is possible to squeeze the drill core 1 with fingers, the deterioration is usually significant, but the squeezing test does not destroy or further damage the core sample - when the core 1 is secured in the tube 11. After manually and visually testing the quality of the drill core 1 , then it can be decided whether it is necessary to take another sample or not.

[0091] Keeping the drill core 1 in the tube 11 has several further significant advantages: it can be kept in the tube 11 during further processing steps (inserted into a slide microtome or a grinding device, for example). If the tube 11 is made of a (biological or technical) plastic or paper / cardboard, it can simply be cut (by hand or by microtome) or grinded (by hand or by machinery) as well. This means that the drill cores 1 can be kept in the best possible condition (straight, unbroken, in correct order and angle, ...) ensured by the tube 11 for as long as possible during the preparation and analysis process. This way, the drill core 1 can be measured and evaluated most easily, accurately and reliably (and better as it has ever been possible to date). This means that the drill cores 1 can stay in the tubes 11 after removal from the tree and increment borer 2 for practically all further steps of preparation and analysis, providing best possible sample quality, allowing the most efficient work (preparation and analysis) and even storing.

[0092] When wooden surfaces are sanded, the cells at the top are usually filled with sanding dust that is practically impossible to remove. This is advantageous for some analyses and measurements. In most cases, however, it is better if the cells are open, for example if cell wall properties are to be measured. This can only be achieved by cutting the surface manually (with, for example, razor blades) or using aproper microtome. Cutting works best when the wood is moist (as in the tree) and even better when it is heated. This is why it is advantageous to close the tube 11 immediately after the core 1 has been removed from the increment borer 2. This retains the moisture in the drill core 1 , which also reduces its deformation. It is even possible to fill in some additional water, if there is still space between the tube wall and the drill core 1 . The wet drill core 1 can then be cut optimally and with minimum effort. If desired, the drill core 1 in the tube 11 can even be heated briefly before cutting, which makes cutting easier and generally improves the quality of the cut.

[0093] If the material of the straw-shaped tube 11 shrinks when heated, as is the case with the shrink tubes 11 commonly used in electronics, for example, such heating ensures that the drill core 1 is still sufficiently securely fixed even if, for example, the upper third or even half of the cross-section is removed (as has been common practice to date when grinding or cutting drill cores 1 ).

[0094] All these advantages of simpler and safer handling with the maximum possible quality of the drill cores 1 are only achieved by the fact that the drill core 1 can be stored in the tube 11 quasi permanently.

[0095] However, the best possible wood sample quality and reliability is only possible if the drill core 1 is inserted into the tube 1 directly during drilling inside the increment borer 2, without torsional stress and correspondingly free of defects (without cracks and fractures, without deformations and adhesions). Therefore, it is the combination of these two new features, the inner geometry of the increment borer 2 (=expanding inner diameter directly after the front cutting edge 5) and the (preferably transparent) tube 11 , that delivers the major advantages referring drill core 1 quality and reliability at lower costs and with less effort compared to the previous situation. This not only reduces the number of cores 1 that need to be taken and thus minimizes the required amount of work. In addition to the increased efficiency, it reduces the damage to the trees because less drill cores 1 need to be taken (and less increment borers 2 are left in trees).

[0096] Finally, the drill core sample can also be quickly and easily identified by labeling the tube 11 with a pen, without the problem of chemically modifying wood properties by the ink when writing directly on the drill core 1 .

[0097] What has been described here for the extraction of drill cores 1 from trees and wood also applies in a similar way to the extraction of soil samples. Here too, it is advantageous to widen the inner diameter of the drill directly after the cutting edge 5 and to insert a preferably transparent, plastic tube 11 beforehand into the borer 2 or bore bit in order to obtain interference-free soil-depth profiles.

[0098] The same applies to the sampling of snow and ice cores 1 . In this field of research, the avoidance of the above mentioned heat effect by friction within the borer 2 or drill bit is even more important for obtaining undisturbed samples.

[0099] Many modifications and other embodiments of the invention set forth herein will come to mind to the one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. List of reference signs

[0100] 1 drill core

[0101] 2 borer

[0102] 3 shaft

[0103] 4 cutting thread

[0104] 5 cutting edge

[0105] 6 hollow space

[0106] 7 first opening

[0107] 8 second opening

[0108] 9 inner diameter

[0109] 10 inner surface

[0110] 11 tube

[0111] 12 stop surface

[0112] 13 inner end

[0113] 14 inner diameter of the tube

[0114] 15 protrusion

[0115] 16 portion

[0116] 17 rear end

Claims

C l a i m s1 . A device for extraction of a drill core (1 ) from a material, comprising: a borer (2) having a longitudinally extending cylindrical shaft (3) with a first end and a second end and with a cutting thread (4) at the first end, wherein a cylindrical hollow space (6) is formed in the shaft (3), wherein the hollow space (6) extends through the whole shaft (3) from the first end to the second end and comprises a first opening (7) at the first end in a center of the cutting thread (4) and a second opening (8) at the second end and wherein the borer (2) is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core (1 ) through the first opening (7) within the hollow space (6) during drilling, c h a r a c t e r i z e d i n t h a t an inner diameter (9) of the hollow space (6) expands beginning from a foremost cutting edge (5) of the cutting thread (4) at the first end in direction to the second end up to a defined distance, thereby forming an expanding inner surface (10).

2. The device according to claim 1 , wherein the device comprises a drill core receiving tube (11 ) which can be inserted in the hollow space (6) through the second opening (8).

3. The device according to claim 2, wherein a radially extending stop, shoulder or stop surface (12) for the tube is formed in the hollow space.

4. The device according to claim 3, wherein the radially extending stop, shoulder of stop surface (12) is formed at an inner end (13) of the expanding inner surface (10).

5. The device according to claim 3 or 4, wherein the stop surface (12) forms an annulus wherein an inner diameter of the annulus is larger than the inner diameter of the hollow space (6) at the foremost cutting edge (5) of the cutting thread (4).

6. The device according to claim 5, wherein an inner diameter (14) of the tube (11 ) is larger or equal than the inner diameter of the annulus.

7. The device according to one of claims 2 to 6, wherein the tube (11 ) is longer than the shaft (3) or longer than the distance between the stop, shoulder or stop surface (12) and the second end.

8. The device according to one of claims 2 to 7, wherein the tube (11 ) is at least partially transparent or at least partially made from a transparent material.

9. The device according to one of claims 2 to 8, wherein the tube (11 ) is at least partially flexible or at least partially made from a flexible material.

10. The device according to one of claims 1 to 9, wherein the cutting thread (4) has a radially extending circumferential protrusion (15), wherein the protrusion (15) radially extends beyond an outer diameter of the shaft (3).11 . The device according to one of claims 1 to 10, wherein at least a portion (16) of the cutting thread (4) is designed for cutting in a backward direction.

12. The device according to claim 11 , wherein at least a part of the portion (16) has an increasing diameter beginning at a rear end (17) of the cutting thread (4) in direction to the first end.

13. The device according to one of claims 1 to 12, wherein the material is a wooden substance, a soil, snow or ice.

14. A system for extraction of a drill core from a material, comprising: a device according to one of claims 1 to 13 and a handle or a driving unit for driving the borer (2).

15. A method for extraction of a drill core (1 ) from a material, particularly by means of a device according to one of claims 1 to 13 or by a system according to claim 14, wherein the device comprises:- a borer (2) having a longitudinally extending cylindrical shaft (3) with a first end and a second end and with a cutting thread (4) at the first end, wherein a cylindrical hollow space (6) is formed in the shaft (3), wherein the hollow space (6) extends through the whole shaft (3) from the first end to the second end and comprises a first opening (7) at the first end in a center of the cutting thread (4) and a second opening (8) at the second end and wherein the borer (2) is designed for being drilled into the material in a forward direction with the first end ahead and for receiving a drill core (1) through the first opening (7) within the hollow space (6) during drilling, c h a r a c t e r i z e d by the following steps:- inserting a drill core receiving tube (11 ) in the hollow space (6) through the second opening (8);- drilling the borer (2) into the material in a forward direction with the first end ahead;- receiving at least a part of the drill core (1) through the first opening (7) within the hollow space (6) during drilling; and- removing the tube (11 ) with the part of the drill core (1 ) or with the drill core (1 ) in the tube (11 ).

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