PORTABLE POWER ROTARY DEVICE PROVIDED WITH DRILL HAVING EARTHWORK AND CUT-OFF FUNCTIONS

Information

  • Patent Application
  • 20170107765
  • Publication Number
    20170107765
  • Date Filed
    September 22, 2014
    10 years ago
  • Date Published
    April 20, 2017
    7 years ago
  • Inventors
    • KIM; Young Goan
Abstract
A rotary device having mounted therein a drill for soil earthwork. The drill includes a shaft and a screw, formed along the outer circumferential surface of the shaft, for earthwork and the transportation of displaced soil. A rotary shaft is formed on the upper part of the shaft. A fixed shaft part is formed on the lower part of the shaft, for being inserted and rotated into the soil. A pair of horizontal blades face each other on the connection part between the shaft and the fixed shaft part. Cutting blades, which are symmetrical with each other, incline downwardly on the pair of horizontal blades. Vertical blades protrude vertically on the upper portion of the lower wing of the screw and, when performing earthwork, soil and tree roots are cut by the cutting blades, and soil lumps, transferred along the screw, are cut again by the vertical blades.
Description
TECHNICAL FIELD

The present invention relates to a portable power rotary device provided with a drill having earthwork and cut-off functions, and more particularly, to a portable power rotary device provided with a drill having earthwork and cut-off functions, which excavates soil and cuts tree roots tangled like a spider's web using cutting blades, formed on a pair of horizontal blades, by inserting a fixed shaft part of the drill rotatably mounted in a rotary body into the soil and fixing the same to its location, and then rotating the drill, and also, cuts the soil again using vertical blades and then transports the soil upwardly through a screw.


BACKGROUND ART

In general, about 65% of our country's total land area (South Korea) is covered by mountain areas including woods and fields, and mountain areas are important factors for establishing country's policies. Therefore, the government aggressively pursues utilization of mountain areas as resources and applying policies.


In recent years, a national afforestation plan is required to prevent yellow dust from China or fine dust or to support “Growing Trees” for North Korea, and cropping and cultivation in mountain areas are increasingly performed for personal purposes along with a well-being trend for living to be 100 years old and a healing trend, and with the increase in high-income specialty crops, scientific farming, and the number of people returning to farming. Therefore, the government is institutionally and actively encouraging people to utilize the mountain areas and is supporting by supplementing the Forest Law, Management of Mountainous Districts of Act, or Promotion Act. Accordingly, short-term forest products such as traditional medicinal hubs, health foods, and wild hubs and vegetables are increasingly cultivated in mountain areas, and fruit trees or seedling are increasingly planted. In addition, farming in mountain areas is increasing to utilize idle farmland and to spread farming in a city.


However, unlike in farmland, mechanization in mountain areas is almost impossible due to the characteristics of the mountain areas, such as steep slopes, obstacles such as trees, incomplete access roads, or the like, and soil conditions of tree roots, grass roots, and stones are poor. In addition, working with manpower has become more difficult due to chronic labor shortage in farm villages, aging society, and evasion of manual labor. Therefore, there is an acute need for development of portable mechanization equipment for agriculture and forestry.


Korean Registration No. 10-1234700 pre-field by the same applicant as the present application and registered discloses a portable power rotary device provided with a drill having earthwork and cut-off functions.


The “portable power rotary device provided with the drill having the earthwork and cut-off functions” is a rotary device having a drill rotatably mounted therein for excavating soil, wherein the drill includes: a shaft part; a screw formed along the outer circumferential surface of the shaft part for excavating soil and also transporting the excavated soil; a rotary shaft formed on the upper part of the shaft part; and a fixed shaft part formed on the lower part of the shaft part for being inserted and rotated into the soil to be excavated, and wherein a pair of auxiliary cutting blades are further formed on one surface of the wing of the screw and vertically protrude therefrom, such that tree roots which are raised along the screw without being removed by horizontal blades during earthwork are completely cut by the auxiliary cutting blades.


The portable power rotary device provided with the drill blades having the earthwork and cut-off functions cuts soil and tree roots using the cutting blades of the drill. However, soil and tree roots may not be completely crushed only by the horizontal cutting blades.


Therefore, the applicant of the present application has developed a portable power rotary device provided with a drill having earthwork and cut-off functions, wherein the drill excavates soil by using cutting blades formed on a pair of horizontal blades, and faces, at a right angle, tree roots which are raised along a screw wave without being cut only by the horizontal blades since most of the tree roots lie horizontally, so that the tree roots can be easily cut and thus an engine output is efficient. In addition, when cut soil is wide and flat, the portable power rotary device provided with the drill having the earthwork and cut-off functions can cut the soil again using a plurality of vertical blades so that the soil can be more finely ground.


DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE
Technical Objects

The present invention has been developed in order to solve the above-mentioned problems, and an object of the present invention is to provide a portable power rotary device provided with a drill having earthwork and cut-off functions, which, when soil is raised along a screw without being cut due to a misaligned angle (roots are horizontal and a blade is also horizontal) when the drill excavates the soil, can completely cut the soil by using a plurality of secondary blades formed perpendicular to a screw wing, and transports the soil upwardly, so that cutting and earthwork can be easily performed.


Another object of the present invention is to provide a portable power rotary device provided with a drill having earthwork and cut-off functions, which includes cutting blades formed on one side of each of a pair of horizontal blades and inclined downwardly therefrom, for easily crushing soil and tree roots when the drill excavates soil, and thus can easily crush the soil and tree roots by using the horizontal blades and the vertical blades when excavating the soil.


Another object of the present invention is to provide a portable power rotary device provided with a drill having earthwork and cut-off functions, which excavates a place where there are many roots such as a mountain area or a place where soil is hard with a medium bore, and excavates a place where there is less obstacle such as roots and soil is comparatively soft with a large bore.


An application of the present invention is to provide a portable power rotary device provided with a drill having earthwork and cut-off functions, which is easy to carry and operate for the purposes of enhancing efficiency of various “earthworks” or “shovel works” such as cultivating a mountain area, cultivating medicinal hubs, digging for seedlings, digging waterway, landscaping, laying out a city vegetable garden, or the like, and of replacing and supplementing a tractor or a management device in a little piece of land or a mountain area where large scale equipment cannot enter.


Technical Solving Means

In order to achieve the above-described objects, the present invention provides a portable power rotary device provided with a drill having earthwork and cut-off functions, wherein the drill for excavating soil is rotatably mounted in the portable power rotary device, and includes: a shaft part; a screw formed along the outer circumferential surface of the shaft part, for excavating soil and transporting the excavated soil; a rotary shaft formed on the upper part of the shaft part; a connection socket installed on the rotary shaft for adjusting length; and a fixed shaft part formed on the lower part of the shaft part for being inserted and rotated into the soil to be excavated, wherein a pair of horizontal blades are formed on the connection part between the fixed shaft part and the shaft part to face each other; the screw has layers formed one on the other and symmetrically and integrally connected to each other on the pair of horizontal blades, for transporting soil upwardly; cutting blades are inclined downwardly to be symmetrical to each other and are integrally formed on the pair of horizontal blades; a plurality of vertical blades protrude vertically from the upper portion of the lower wing of the screw and are formed to be spaced apart from each other at a predetermined distance; and, when soil is excavated, soil and tree roots are cut by the cutting blades, and soil lumps, transferred along the screw, are cut again by the vertical blades.


The cutting blades formed on the horizontal blades may have blade parts formed on lower ends thereof and inclined inwardly, for cutting soil during excavation and transporting the soil toward the screw.


The vertical blades formed on the upper portion of the lower wing of the screw may have edges formed in a saw-tooth shape or a diamond shape and inclined, and are formed by welding or attachably or detachably formed.


The fixed shaft part may have a cutout groove formed on the center of the lower end thereof and thus has excavation blades twisted to cross each other, for digging into soil by itself without pressing the device.


The fixed shaft part may have a pointed part formed at the lower end thereof and a spiral formed on the upper circumferential surface thereof, for inducing the fixed shaft part to dig into soil by itself without pressing the device.


The connection socket may be connected to the rotary shaft to adjust the length of the drill, so that a worker works in a comfortable position and thus fatigue is reduced, or when it is necessary to increase excavation depth, a connection socket of a different size may be connected and used.


Advantageous Effects

The portable power rotatory device provided with the drill having the earthwork and cut-off functions of the present invention as described above can easily cut soil and tree roots by using the cutting blades and the horizontal blades when the drill excavates soil, and cut the soil again by using the vertical blades formed on the wing of the screw when the soil is transported upwardly by the screw, so that the crushed soil and tree roots can be easily transported upwardly by the screw and there is an effect of preventing a shock from being applied to the screw.


In addition, the rotary device may be provided with a small bore to perforate a steel pipe column or a wall column, and may be provided with a medium bore to excavate a place where there are many roots such as a mountain area or comparatively hard soil such as weathered soil, and also may be provided with a large bore to effectively excavate a place in which there is less obstacle or comparatively soft soil.


In addition, the portable power rotary device provided with the drill having the earthwork and cut-off functions provides the drill which is rotatably mounted in the rotary body and which includes the screw, the fixed shaft part, the horizontal blades, and the cutting blades, and excavates soil and cuts tree roots with the cutting blades by inserting and fixing the fixed shaft part into soil and then rotating the drill, and then transports the soil and the tree roots using the screw, so that the drill can be prevented from leaving from its location during the earthwork and the device is easy to carry, and earthwork and rotary (crushing) functions can be easily performed simultaneously.


Accordingly, the functions of a horizontally moving large work device such as a tractor or a management device can be converted into a vertical rotation type, and the device can be miniaturized within a size of about 10 kg. Therefore, abandoned land can be effectively utilized and manpower can be greatly reduced, and thus there is an effect of making a contribution to agriculture and forestry.


In addition, the device is designed to have a high speed and light load rather than a low speed and heavy load as in related art methods, so that particles of soil can be very finely ground (fine powder) by high speed rotation (about 150 RPM), and thus easy cropping and easy harvesting of root vegetables can be more surely enhanced and guaranteed by forming soil pores (aggregated structure), enhancing air permeability, removing harmful microorganism, and removing roots.


In addition, the drill can be prevented from being moved during the earthwork and is easy to carry and has good workability, and as a result of the earthwork thereof, there are effects of easy cropping and easy and complete harvesting of high price medicinal herb roots such as wood-cultivated ginseng by forming soil pores, enhancing air permeability, removing harmful microorganism, and removing tree roots.


In addition, there is an effect of using the connection socket which is able to easily adjust the length of the rotary shaft according to desired depth or the height of a worker.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a bottom perspective view showing a portable power rotary device provided with a drill having earthwork and cut-off functions according to the present invention;



FIG. 2 is a perspective view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention;



FIG. 3 is a front view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention;



FIG. 4 is a use state view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention;



FIG. 5 is a perspective view showing another embodiment of the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention; and



FIG. 6 is a front view showing another embodiment of the portable power rotary device with the drill having the earthwork and cut-off functions according to the present invention.





BEST MODE FOR EMBODYING THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the present invention can be implemented in different forms and is not limited to the embodiments described below.



FIG. 1 is a bottom perspective view showing a portable power rotary device provided with a drill having earthwork and cut-off functions according to the present invention, FIG. 2 is a perspective view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention, FIG. 3 is a front view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention, FIG. 4 is a use state view showing the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention, FIG. 5 is a perspective view showing another embodiment of the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention, and FIG. 6 is a front view showing another embodiment of the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention.


The present invention relates to a portable power rotary device provided with a drill having earthwork and cut-off functions, and more particularly, to a portable power rotary device provided with a drill having earthwork and cut-off functions, which excavates soil and cuts tree roots tangled like a spider's web using cutting blades, formed on a pair of horizontal blades, by inserting a fixed shaft part of the drill rotatably mounted in a rotary body into the soil and fixing the same to its location, and then rotating the drill, and also, cuts the soil again using vertical blades and then transports the soil upwardly through a screw.


Referring to FIGS. 1 to 6, the portable power rotary device provided with the drill having the earthwork and cut-off functions according to the present invention will be described hereinafter.


The portable power rotary device 10 (hereinafter, referred to as a rotary device) provided with the drill having the earthwork and cut-off functions of the present invention has a drill 30 rotatably mounted therein for excavating soil 50, and the rotary device 10 includes a rotary body 20 and the drill 30.


As well-known and widely used, the rotary body 20 has a decelerator and a driving engine embedded therein, and has a rotary shaft 31 of the drill 30 attachably and detachably connected thereto to pivot about a perforation shaft 21, and then rotates the connected drill 30 to use the drill 30 for many purposes, such as planting a seedling, earthwork in a place which equipment cannot enter or a little piece of land, excavating a hole for installing a fence wood pillar, or perforating a lumber pillar of a Ginseng field. Therefore, an inner structure and an operation relationship of the rotary body 20 will not be described in detail.


The portable power rotary device 10 provided with the drill having the earthwork and cut-off functions of the present invention is the rotary device 10 having the drill 30 rotatably mounted therein for excavating soil 50, and the drill 30 is made of metallic material and is designed to excavate soil 50 in a mountain area. The drill 30 may include a shaft part 32 formed of a circular metal rod, a screw 35a and 35b formed along the outer circumferential surface of the shaft part 32, for excavating soil 50 and transporting the excavated soil, a rotary shaft 31 formed on the upper part of the shaft part 32, a connection socket 40 formed on the rotary shaft 31 for adjusting length, and a fixed shaft part 37 formed on the lower part of the shaft part 32 for being inserted and rotated into the soil 50 to be excavated.


A pair of horizontal blades 33 are formed on the connection part between the fixed shaft part 37 and the shaft part 32 to face each other. The screw 35a and 35b has layers formed one on the other and symmetrically and integrally connected to each other on the pair of horizontal blades 33, for transporting soil upwardly. Cutting blades 34 are inclined downwardly to be symmetrical to each other and are integrally formed on the pair of horizontal blades 33. A plurality of vertical blades 36 protrude vertically from the upper portion of the lower wing of the screw 35a and 35b, and are formed to be spaced apart from one another at a predetermined distance. When soil is excavated, soil and tree roots are cut by the cutting blades 34, and lumps of soil 50, transferred along the screw 35a and 35b, are cut again by the vertical blades 36.


The cutting blades 34 formed on the horizontal blades 33 have blade parts 34A formed on lower ends thereof and inclined inwardly, for cutting tree roots during excavation and transporting soil 50 toward the screw 35a and 35b.


The vertical blades 36 formed on the upper portion of the lower wing of the screw 35a and 35b have edges formed in a saw-tooth shape or a diamond shape and inclined, and are formed by welding or attachably or detachably formed.


The edges of the vertical blades 36 are inclined so as to prevent an overload from being applied to the screws 35a and 35b when lumps of soil 50 and tree roots are cut.


The fixed shaft part 37 has a cutout groove 37a formed on the center of the lower end thereof and thus has excavation blades 37b twisted to cross each other, for digging into soil by itself without pressing the device.


According to another embodiment, as shown in FIG. 5, the fixed shaft part 37 has a pointed part 37c formed at the lower end thereof and a spiral 37d formed on the upper circumferential surface thereof, for inducing the fixed shaft part 37 to dig into soil by itself without pressing the device.


The fixed shaft part 34 is fixed to the lower end of the shaft part 32 by welding, and is inserted into soil to be excavated, for preventing the drill 30 from being moved.


The connection socket 40 is connected to the rotary shaft 31 to adjust the length of the drill 30, so that a worker can work in a comfortable position and thus fatigue can be reduced, or when it is necessary to increase excavation depth, a connection socket 40 of a different size may be connected and used.


Mode for Embodying the Invention

The use state of the portable power rotary device 10 provided with the drill having the earthwork and cut-off functions as described above will be described. Referring to FIG. 4, a user grips the rotary body 20 having the drill 30 mounted thereon and fixes the fixed shaft part 37 of the drill 30 in soil to be excavated, and then rotates the drill 30 by driving the rotary body 20.


Alternatively, the user may rotate the drill 30 and then insert the rotating fixed shaft part 37 to soil to be excavated, and the fixed shaft part 37 may be easily inserted into the soil by the spiral 37d of the fixed shaft part 37.


Thereafter, the drill 30 being inserted into the soil 50 by the fixed shaft part 37 and being supported is rotated, and the blade part 34a of the cutting blades 34 formed on the horizontal blades 33 excavate the soil 50 and also cut tree roots. The excavated soil is cut again by the plurality of vertical blades 36 formed on the lower wing of the screw 35a and 35b and the soil is transported upwardly by the screw 35a and 35b and is discharged to the outside. In this way, a series of earthworks is finished.


In this case, the plurality of vertical blades 36 are provided on the wing of the screw 35a and 35b, and thus cut the soil 50 raised along the screw 35a and 35b again, and the crushed soil and tree roots are transported upwardly by the screw 35a and 35b, so that earthwork can be easily performed.


Since the lumps of the soil 50 are cut by the vertical blade 36 as described above, the soil is prevented from being tangled and enclosing the shaft part 32 and thus a load can be prevented from being applied to an engine.


The cutting blades 34 formed on the horizontal blades 33 excavate the soil and simultaneously cut the tree roots, and the excavated soil and the cut tree roots are guided by the screw 35a and 35b and the soil lumps are cut again by the vertical blades 36 and are transported upwardly.


Inconvenience that may be caused by the drill 30 being shaken by imbalance during the earthwork or not being easily mounted on an inclined surface and sliding out can be prevented by the fixed shaft part 37, and soil can be very finely and lightly ground by rotating the left and right excavation blades 37b, which are thin and strong, at high speed, so that a plowing effect and a grinding effect of a management device can be obtained simultaneously. Therefore, a subsequent work can be easily performed and there are effects of forming pores of soil, enhancing air permeability, and reducing harmful microorganism.


In addition, tree roots may be raised without being cut due to a misaligned angle of the cutting blades 34. In this case, the tree roots may be exactly cut again by the horizontal blades 33, so that the engine can be prevented from being stopped by the tension of the roots, and the work can be continuously and smoothly performed.


In addition, the plurality of connection sockets 40 may be provided on the rotary shaft 31 of the drill 30 to adjust the height of the device according to a gradient or a difference in heights of workers, or desired excavation depth. By selecting and connecting the connection sockets 40, the drill can be extended by 15-40 cm or higher in comparison to basic height of the drill.


In the rotary device 10 described above, the drill 30 may be provided with a small bore to perforate and may be provided with a medium bore to excavate a place where there are many roots such as a mountain area or a place where soil is hard, and may be provided with a large bore to excavate a place where there is less obstacle such as roots and soil is comparatively soft.


Accordingly, in a mountain area or slope or an adverse condition where large equipment cannot enter, the device can be easily carried and moved, and also, can perform very efficient earthworks and rotary works with low power. In addition, various functions including the roles of an ultraminiaturized excavator, such as making a furrow, digging waterway, or ridging, can be performed by bending or shaking the device forwardly and backwardly and to the left or right during the work.


Compared to a rotary machine or a management device, the present invention can minimize a price and weight, and is far superior in view of mobility and fuel efficiency and the cost of maintenance is extremely low.


As a result of performing works using the above-described rotary device 10, soil can be finely excavated and agitated, so that root respiration can be enhanced and the growth of plants can be accelerated. In particular, the present invention relates to the portable power rotary device provided with the blade part 36a of the sharp vertical cutting blades 34, in addition to the horizontal blades 33 having dial earthwork and cut-off functions, which can easily perform the works without damaging roots during harvest, and also, can make a contribution to public functions such as flood prevention by enhancing a water-containing function in a mountain area.


Therefore, the present invention can utilize mountain areas as resources and enhance farmland efficiency, and also can perform very efficient works in substituting for tree-planting works such as landscaping or afforesting, traditional “shovel” works or rotary works, which depend on labor force in various construction sites. Therefore, the present invention can make a great contribution to elimination of labor and energy saving, and also can make a contribution to effectiveness thereof and industry.


As described above, the present invention relates to a device which is easy to carry and operate for the purposes of enhancing efficiency of various “earthworks” or “shovel works” such as cultivating a mountain area, cultivating medicinal hubs, digging for seedlings, digging waterway, landscaping, laying out a city vegetable garden, or the like, and of replacing and supplementing a tractor or a management device in a little piece of land or a mountain area where large scale equipment cannot enter.


In addition, the present invention provides the portable power rotary device provided with the drill having the earthwork and cut-off functions, which can minimize mechanization of the rotary device so that anybody can simply operate the device, and shows excellent efficiency 5-10 times higher than that of manpower works, and thus enhances quality of soil by forming pores, enhancing air permeability, and reducing harmful microorganism, and also improves efficiency such as easy cropping and easy harvesting of roots, and enables deep plowing, agitating, and pulverizing.


While preferred embodiments of the present invention have been described, the present invention may make various changes and use equivalents. It is obvious that the present invention can make appropriate changes to the above-described embodiments and equally apply the embodiments. Accordingly, the above-described matters do not limit the scope of the present invention which is defined by the limit of the claims presented below.


While exemplary embodiments have been particularly described above, it would be obvious to those of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the present invention.


INDUSTRIAL APPLICABILITY

Therefore, the present invention can utilize mountain areas as resources and enhance farmland efficiency, and also can perform very efficient works in substituting for tree-planting works such as landscaping or afforesting, traditional “shovel” works or rotary works, which depend on labor force in various construction sites. Therefore, the present invention can make a great contribution to elimination of labor and energy saving, and also can make a contribution to effectiveness thereof and industry.


As described above, the present invention relates to a device which is easy to carry and operate for the purposes of enhancing efficiency of various “earthworks” or “shovel works” such as cultivating a mountain area, cultivating medicinal hubs, digging for seedlings, digging waterway, landscaping, laying out a city vegetable garden, or the like, and of replacing and supplementing a tractor or a management device in a little piece of land or a mountain area where large scale equipment cannot enter.

Claims
  • 1. A portable power rotary device provided with a drill having earthwork and cut-off functions, wherein the drill for excavating soil is rotatably mounted in the portable power rotary device, and comprises: a shaft part; a screw formed along the outer circumferential surface of the shaft part, for excavating soil and transporting the excavated soil; a rotary shaft formed on the upper part of the shaft part; a connection socket installed on the rotary shaft for adjusting length; and a fixed shaft part formed on the lower part of the shaft part for being inserted and rotated into the soil to be excavated, wherein a pair of horizontal blades are formed on the connection part between the fixed shaft part and the shaft part to face each other; the screw has layers formed one on the other and symmetrically and integrally connected to each other on the pair of horizontal blades, for transporting soil upwardly; cutting blades are inclined downwardly to be symmetrical to each other and are integrally formed on the pair of horizontal blades; a plurality of vertical blades protrude vertically from the upper portion of the lower wing of the screw and are formed to be spaced apart from each other at a predetermined distance; and, when soil is excavated, soil and tree roots are cut by the cutting blades, and soil lumps, transferred along the screw, are cut again by the vertical blades.
  • 2. The portable power rotary device of claim 1, wherein the cutting blades formed on the horizontal blades have blade parts formed on lower ends thereof and inclined inwardly, for cutting soil and tree roots during excavation and transporting the soil toward the screw.
  • 3. The portable power rotary device of claim 1, wherein the vertical blades formed on the upper portion of the lower wing of the screw have edges formed in a saw-tooth shape or a diamond shape and inclined, and are formed by welding or attachably or detachably formed.
  • 4. The portable power rotary device of claim 1, wherein the fixed shaft part has a cutout groove formed on the center of the lower end thereof and thus has excavation blades twisted to cross each other, for digging into soil by itself without pressing the device.
  • 5. The portable power rotary device of claim 1, wherein the fixed shaft part has a pointed part formed at the lower end thereof and a spiral formed on the upper circumferential surface thereof, for inducing the fixed shaft part to dig into soil by itself without pressing the device.
  • 6. The portable power rotary device of claim 1, wherein the connection socket is connected to the rotary shaft to adjust the length of the drill, so that a worker works in a comfortable position and thus fatigue is reduced, or when it is necessary to increase excavation depth, a connection socket of a different size is connected and used.
Priority Claims (1)
Number Date Country Kind
10-2014-0040279 Apr 2014 KR national
PCT Information
Filing Document Filing Date Country Kind
PCT/KR2014/008771 9/22/2014 WO 00