JP2003003778A - Self-propelling young tree planting hole excavator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-propelling young tree planting hole excavator capable of vertically and easily excavating a young tree planting hole even in a slope and, further, easily putting the root of the young tree into the excavated young tree planting hole. SOLUTION: A hole excavator 2 is mounted on a working machine arm 7 of a hydraulic backhoe in a rise and fall manner, the working machine arm 7 and the hole excavator 2 are vertically oscillated and turned to enable the young tree planting hole to vertically and easily excavate even in the slope. The hole excavator 2 includes a mounting section 20, a rotational driving section 21, an excavation section 22 and an excavating section 23, and the roots of plants are cut along the inside circumference of the excavated hole to facilitate the planting of the young tree thereinto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-propelled seedling planting hole excavator for excavating a seedling planting hole for planting a seedling on the ground.

[0002]

2. Description of the Related Art Afforestation work is generally roughly divided into two operations: a work for digging a hole for planting seedlings (hereinafter referred to as a seedling planting hole) in the ground and a work for putting a seedling in the dug seedling planting hole. The above-mentioned work for digging a seedling planting hole is generally carried out by a worker who holds a scoop or a specially-shaped drilling tool by hand.

[0003]

[Problems to be Solved by the Invention] It is a heavy labor for an operator to manually dig a seedling planting hole. In particular, when planting trees on a slope of a mountain, since a sapling planting hole is dug on a sloping land, the worker digs a sapling planting hole on the sloping land while maintaining a physical balance, which is a heavy labor.

Since the seedlings are planted vertically, it is preferable to dig the seedling planting holes vertically. However, as described above, the worker manually digs, so it is difficult to vertically dig a seedling planting hole. In particular, as mentioned above, it is difficult to dig a seedling planting hole vertically on a slope.

When weeds such as mountains and wildlands and plants such as bamboo are planted, the weeds and the plants such as bamboo are cut down and then a seedling planting hole is dug. In this case, since roots of weeds and bamboos remain in the ground, it is difficult to dig a seedling planting hole for the roots of the plants. Also,
The roots project into the dug out planting holes and it is difficult to put the seedlings.

The present invention has been made to solve the above problems. It is a first object of the present invention to provide a self-propelled seedling planting hole excavator that can easily excavate a seedling planting hole. A second object of the present invention is to provide a self-propelled seedling planting hole excavator that can excavate a seedling planting hole vertically. A third object of the present invention is a self-propelled seedling planting hole excavator that can easily excavate a seedling planting hole even if there is a root in the ground and does not interfere with the insertion of a seedling by the root in the soil. That is.

[0007]

[Means for Solving the Problems and Actions and Effects] The first invention is to excavate the soil by rotating it and discharge the excavated soil to form a cup-shaped hole in the formation surface, and the excavating portion 22. The hole excavator 2 having a root cutting part 23 for cutting the roots of the vegetation on the inner peripheral surface is attached to the working machine arm 7 installed on the upper revolving structure 6 rotatably mounted on the upper part of the traveling structure 3 so as to be elevated and lowered. It is a self-propelled seedling planting hole excavator.

According to the first aspect of the present invention, the work vehicle 1 travels on a sloping ground or a flat ground, and the upper revolving structure 6 is swiveled, so that the hole excavator 2 can be located at any position on the sloping ground or a flat ground. . By swinging the working machine arm 7 downward in the above-described state, a seedling planting hole can be easily excavated at an arbitrary position on a sloping ground or a flat ground without manpower. Therefore, a seedling planting hole can be easily excavated at an arbitrary position on a sloping land or a flat land.

Further, the hole excavator 2 can be made vertical to the ground by swinging the working machine arm 7 and the hole excavator 2 up and down according to the inclination angle of the ground. Therefore, a seedling planting hole can be vertically drilled at an arbitrary position on a sloping land or a flat land.

The roots in the ground are cut along the periphery of the excavated hole, and the roots are in a clean state without protruding from the inner surface of the excavated seedling planting hole. Therefore, even if there are plant roots in the ground, you can easily excavate the sapling planting hole, and the roots of the planting tree do not get in the way when putting the saplings in the seedling planting hole,
Easy to put seedlings.

Combined with the above, a part of the tree planting work can be mechanized, and the tree planting work efficiency can be improved.

In a second aspect of the present invention, in the first aspect of the present invention, the hole excavator 2 is attached to the working machine arm 7 and is integrally combined with the attaching section 20, and the excavating section 22 and the root cutting section 2 are combined.
3 is a self-propelled seedling planting hole excavator in which a rotary drive unit 21 for rotationally driving 3 is provided, and the rotary drive unit 21, the excavation unit 22, and the root cutting unit 23 can be separately connected.

According to the second aspect of the invention, the hole excavator 2 is mounted by mounting the mounting portion 20 on the working machine arm 7 so as to be vertically swingable.
Can be easily attached to the working machine arm 7 so as to be vertically swingable.

Further, by rotating the excavating section 22 and the root cutting section 23 by the rotary drive section 21, it is possible to perform hole excavation and root cutting. Therefore, the seedling planting hole can be easily and surely excavated.

Since the excavating portion 22 and the root cutting portion 23 can be replaced with those having different diameters, seedling planting holes having different hole diameters can be excavated.

In a third aspect of the invention, in the second aspect, the mounting portion 20 has a coupling portion that is coupled to the working machine arm 7 and the tilt link 14, and the rotary drive portion 21 is a hydraulic pressure mounted on the mounting portion 20. A motor 30 and a rotating body 32 concentrically connected to an output shaft 42 of the motor 30 are provided.
2 is a self-propelled seedling planting hole excavator having a connecting portion 33 that connects the excavating portion 22 at a position concentric with 2.

According to the third aspect of the present invention, the excavation section 22 and the root cutting section 23 can be rotated by the hydraulic motor 30. Further, since the output shaft 42 of the hydraulic motor 30 and the rotating body 32 are concentric, and the rotating body 32, the excavating portion 22, and the root cutting portion 23 are concentric, the excavating portion 22 and the root cutting portion 23 are connected to the hydraulic motor 30. It can be rotationally driven by the output shaft 42 of FIG. Therefore, the hydraulic motor 30 can accurately excavate the seedling planting hole.

In a fourth aspect of the invention, in the third aspect of the invention, the excavation portion 22 has a shape in which a spiral excavation blade 61 is fixed to the tip of a shaft 60, and the shaft 60 is attached to and detached from the connecting portion 33 of the rotating body 32. The root cutting portion 23 has such a shape that the root cutting portion 23 is fitted and attached to the shaft 60 so that the root cutting portion 23 can freely slip out, and a joint cylinder 72 is provided between the excavation blade 61 and the root cutting portion 23 of the shaft 60. It is a self-propelled seedling planting hole excavator that can be detachably fitted.

According to the fourth aspect of the invention, the shaft 60 is attached to the rotating body 32.
By removing it from the shaft 60
You can get out. Therefore, when either the excavation part 22 or the root cutting part 23 is damaged, it can be replaced.

Further, since the joint cylinder 72 can be fitted to the shaft 60, by sequentially fitting the joint cylinder 72 and the root cutting portion 23 in the above-mentioned state, the excavation portion 22 and the root The distance to the cut portion 23 can be changed. Therefore, the height of the root cutting portion 23 can be adjusted.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a self-propelled seedling planting hole excavator A includes a work vehicle 1 and a hole excavator 2. The work vehicle 1 includes a lower vehicle body 4 provided with a crawler type traveling body 3, an upper revolving body 6 mounted on the lower vehicle body 4 by a revolving mechanism 5 so as to be revolvable within a range of 360 degrees, and the upper revolving body 6 It has a working machine arm 7 attached to the upper and lower parts so as to be swingable up and down. The working machine arm 7 includes a first arm (boom) 8 provided on the up-and-down swing body 6 so as to be vertically swingable, and a second arm (arm) provided at a tip end portion of the second arm 8 so as to be vertically swingable. 9 is equipped. The first arm 8 is vertically swung by a first arm cylinder (boom cylinder) 10. The second arm 9 is vertically swung by a second arm cylinder (arm cylinder) 11. In the second arm 9,
A hole excavator cylinder (bucket cylinder) 12 and a link 13 are provided. A piston lot 12a of the hole excavator cylinder 12 and a link 13 are vertically swingably connected, and a tilt link 14 is vertically swingably connected to the connecting portion.

As described above, in this embodiment, the work vehicle 1 is a crawler type traveling hydraulic excavator, and the hole excavator 2 is attached to the second arm 9 thereof instead of the bucket.
Therefore, the hole excavator 2 is an attachment of the crawler type traveling hydraulic excavator. The work vehicle 1 is not limited to the crawler type traveling hydraulic excavator, but may be any self-propelled vehicle in which the work machine arm 7 is attached to the upper swing body 6 so as to be vertically swingable. Further, the traveling body 3 is preferably a crawler type from the standpoint of traveling on slopes, but is not limited to the crawler type.
It may be a tire type or a combination of a crawler type and a tire type.

The hole excavator 2 is mounted on the working machine arm 7 of the working vehicle 1 so as to be raised and lowered. This hole excavator 2
Rotate to scrape the soil, move the scraped soil upwards and discharge it, form a cup-shaped hole in the stratum surface, cut the root of the plant on the inner peripheral surface of the hole along the hole, The discharged soil is pushed away from the periphery of the hole.

For example, the hole excavator 2 has a mounting portion 20.
, Rotary drive unit 21, excavation unit 22, and root cutting unit 23
And, it has an earth pushing part 24. The mounting portion 20 is the second
The tip of the arm 9 and the tip of the tilt link 14 are vertically swingably connected. The rotation driving part 21 is integrally combined with the lower part of the mounting part 20. The excavation unit 22 is rotated by the rotation driving unit 21 to scrape the soil, move the scraped soil upward, and discharge the soil, thereby forming (drilling) a cup-shaped hole in the stratum surface. . The root cutting portion 23 is provided above the excavation portion 22. The root cutting section 23 is rotationally driven by the rotary driving section 21, and cuts the roots of the plants on the circumferential surface of the hole excavated by the excavating section 22 along the hole. The earth pushing part 2
4 is provided above the root cutting portion 23. The earth displacement unit 24 is rotationally driven by the rotational drive unit 21,
The soil moved upwards is pushed away from the periphery of the hole to prevent the excavated soil from accumulating on the periphery of the hole. The excavation portion 22, the root cutting portion 23, and the earth displacement portion 24 are detachably connected.

Next, an example of a specific shape of the hole excavator 2 will be described with reference to FIGS. 2, 3, 4 and 5. The mounting portion 20 includes a horizontal plate 20a and a pair of vertical plates 20 as shown in FIG.
b is a substantially U-shaped upward shape, and the pair of vertical plates 20b has a first
A pin hole 25 and a second pin hole 26 are formed. As shown in FIG. 1, the tip end portion of the second arm 9 projects between the pair of vertical plates 20b, and is vertically swingably connected by the first pin 27 that is inserted through the first pin hole 25. The tip end of the tilt link 14 projects between the pair of vertical plates 20b, and is vertically swingably connected by a second pin 28 inserted into the second pin hole 26. Therefore, by expanding and contracting the piston lot 12a of the hole excavator cylinder 12, the mounting portion 20 (hole excavator 2) swings up and down with respect to the second arm 9 (work implement arm 7).

The rotary drive unit 21 includes a hydraulic motor 30.
And a speed reducer 31 provided on the output side thereof, and a rotating body 3 rotatably driven by the hydraulic motor 30 provided on the output side thereof.
2 and a connecting body 33 provided at the rotation center position on the lower surface of the rotating body 32. The hydraulic motor 30 is fixed to the lower surface of the lateral plate 20a of the mounting portion 20. The upper portion of the hydraulic motor 30 projects between the pair of vertical plates 20b to protect the upper portion. The rotating body 32 is provided on the output side of the speed reducer 31.
Is detachable, for example, fixed with bolts.

An example of specific shapes of the hydraulic motor 30 and the speed reducer 31 will be described with reference to FIG. Hydraulic motor body 4
Reference numeral 0 is a cylindrical shape, and is provided with a mounting flange 41. The mounting flange 41 is fixed to the horizontal plate 20a with bolts 34. A cylinder block, a swash plate, etc. are provided in the hydraulic motor main body 40, and a plurality of pistons fitted in a plurality of cylinder holes of the cylinder block slide along the swash plate. Then, the output shaft 42 rotates by supplying the pressure oil to the cylinder hole. Since this structure is well known in the art, its illustration is omitted. A cylinder 43 is rotatably attached to the outer peripheral surface of the hydraulic motor body 40. The cylindrical body 43 has a mounting flange 44. This cylindrical body 43 is the output side of the speed reducer 31. The rotating body 32 is fixed to the mounting flange 44 of the cylindrical body 43 with bolts 45.

The speed reducer 31 has an input shaft 46 connected to the output shaft 42 (spline fitting), a first sun gear (sun gear) 47 and a second sun gear 48 provided on the input shaft 46.
A first carrier 50 having a first planetary gear (planetary gear) 49 meshing with the first sun gear 47, and a second carrier 52 having a second planetary gear (planetary gear) 51 meshing with the second sun gear 48. ing. The first sun gear 47 is fixed to the output shaft 46. The first planetary gear 49 meshes with a ring gear 53 formed on the inner peripheral surface of the cylindrical body 43, and the first carrier 50 is fixed to the second sun gear 48 (spline fitting). The second
The sun gear 48 is rotatable around the output shaft 46. The second planetary gear 51 meshes with the ring gear 53 of the cylindrical body 43, and the second carrier 52 is supported (spline-fitted) by the hydraulic motor body 40 and does not rotate.

The output shaft 42 is rotated by the input shaft 46, the first
This is transmitted to the sun gear 47 and the first carrier 50 rotates.
The rotation of the first carrier 50 is transmitted to the second sun gear 48,
The second planetary gear 51 is rotated to rotate the cylinder 43 at a low speed. That is, the speed reducer 31 is a two-stage planetary gear type speed reducer.

The rotating body 32 is a cylindrical body having a bottom, and is fitted on the outer periphery of the cylindrical body 43. The opening edge of the rotating body 32 contacts the mounting flange 44 of the cylindrical body 43, and is fixed by the bolt 45. The rotating body 32 is the hydraulic motor 3
It is concentric with the zero output shaft 42. The connecting body 33 is provided at the rotation center position of the rotating body 31, and the connecting body 33 is concentric with the output shaft 42 of the hydraulic motor 30. As described above, since the lower portions of the speed reducer 31 and the hydraulic motor 30 are covered with the rotating body 32, the lower portions of the speed reducer 31 and the hydraulic motor 30 can be protected and damage can be prevented.

The rotary drive unit 21 may directly connect the output shaft 42 of the hydraulic motor 30 to the rotating body 32 without using the speed reducer 31. That is, the rotary drive unit 21 has the hydraulic motor 30 and the rotating body 32 concentrically connected to the output shaft 42, and the connecting portion 33 is connected to the rotating body 32 by the output shaft 42.
Any shape may be used as long as it has a concentric shape. Preferably, the rotating body 32 has a tubular shape, and the rotating body 32 is used as the hydraulic motor main body 4
It is rotatably supported on the outer peripheral surface of 0.

As shown in FIGS. 2 and 4, the excavation section 22 is an auger having a spiral excavation blade 61 fixed to a shaft 60, and the shape of the auger is a hole matching a pot containing seedlings. For example, the shape is such that a cup-shaped hole can be excavated.
A tip drilling blade 62 is fixed to the tip of the shaft 60.
The shaft 60 has a hollow shape with a circular cross section, and an upper end portion of the shaft 60 is detachably connected to the connecting body 33 of the rotating body 32. For example, a square shaft 63 is fixed to the upper end of the shaft 60. The square shaft 63 is fitted in the square hole 33a of the connecting body 33 and is connected by a bolt nut 64. Therefore, the excavation unit 22 is arranged concentrically with the output shaft 42 of the hydraulic motor 30 in the rotary drive unit 21,
Removably connected. Further, since the shaft 60 has a hollow shape, it is lightweight, and the hole excavator 2 can be vertically swung with a small force.

As shown in FIG. 2, FIG. 4, and FIG. 5, the root cutting portion 23 has a plurality of stays 66 radially fixed to a tubular body 65, and a plurality of arcuate cutting blades 67 are substantially attached to the stays 66. It is fixed in a cylindrical shape. The cylindrical body 65 is fitted onto the outer peripheral surface of the shaft 60 so as to be able to slip out. The arcuate cutting blades 67 are arranged at intervals in the circumferential direction such that the sharpened blade portions 67a face in the excavation rotation direction (arrow a). The plurality of arcuate cutting edges 67 are arranged along a circular locus concentric with the center of the shaft 60 (the center of rotation of the excavation portion 22).
Thereby, a substantially cylindrical cutting edge is formed. The diameter of the circular locus is slightly larger than the maximum excavation diameter of the excavation section 22.

A support ring 68 is fixed at a position slightly above the excavation blade 61 of the shaft 60. The lower ends of the cylinders 65 are engaged with the support ring 68 so as not to rotate relative to each other. For example, the projection 65a of the support ring 68 is engaged with the recess 65a formed on the lower end surface of the tubular body 65. Because of this, the cylindrical body 65 (root cutting portion 23) rotates together with the shaft 60 (excavation portion 22).

The earth displacement portion 24 is shown in FIGS. 2, 4 and 5.
As shown in FIG. 3, a cylindrical body 69 is fitted into the outer peripheral surface of the shaft 60 so as to be slidable, and a plurality of, for example, a pair of push-out plates 70 fixed to the cylindrical body 69 in the radial direction.
The pair of displacement plates 70 face each other in the radial direction and are convexly curved in the rotation direction. The pair of push-out plates 70 project outwardly from the arcuate cutting blade 67 of the root cutting portion 23. The lower end of the tubular body 69 and the upper end of the tubular body 65 are engaged with each other so as not to rotate. For example,
A recess 69a formed on the lower end surface of the tubular body 69 is fitted in a protrusion 65b formed on the upper end surface of the tubular body 65. The cylindrical body 6
9 and the shaft 60 are connected by a bolt nut 71.

Because of this, the shaft 60 (excavator 2
The cylindrical body 69 (excavation part 24) rotates together with 2).

The shaft 60 projects above the cylinder 69 of the push-out section 24. A plurality of joint cylinders 72 are sequentially fitted into the projecting portion so that they can be removed.
Each of the joint cylinders 72 has a shaft 60 and a bolt nut 7 attached thereto.
Connected with 3. Each of the joint cylinders 72 has a recess 72a on the lower end surface and a protrusion 72b on the upper end surface, and the vertically adjacent joint cylinders 72 are engaged with each other so as not to rotate. That is, each joint cylinder 72, the cylinder 65, and the cylinder 69 have the same shape.

Because of this, by loosening the bolt nut 64 and pulling it out, the angular shaft 63 of the shaft 60 is connected to the connecting member 33.
Can be extracted from. Therefore, the excavation section 22 can be removed from the rotary drive section 21 together with the root cutting section 23 and the soil discharging section 24.

In the above-mentioned state, each bolt nut 73, 71
By loosening and pulling out, the joint cylinder 72, the soil discharging portion 24, and the root cutting portion 23 can be pulled out from the shaft 60 and removed to separate the excavation portion 22, the root cutting portion 23, and the soil discharging portion 24. , Can be connected by the reverse operation described above. That is, the excavation portion 22, the root cutting portion 23, and the earth shaving portion 24 are connected to each other in a separable manner. Therefore, when at least one of the excavation part 22, the root cutting part 22, and the earth discharging part 23 is damaged,
Only the damaged one can be replaced.

The excavation part 22 and the root cutting part 23, the root cutting part 23 and the earth shoveling part 24 are connected by bolts, respectively, and the shaft 60 is connected to the earth shoveling part 24, whereby the excavation part 22 and the root cutting part are cut. The part 23 and the earth displacement part 24 may be detachably connected.

Further, by fitting the joint cylinder 72 between the support ring 68 and the cylinder 65, the root cutting portion 23
Can be separated from the excavation portion 22, and the attachment position of the root cutting portion 23 can be increased. In addition, by fitting the joint cylinder 72 between the cylinder 65 and the cylinder 69, the earth displacement part 24
Can be separated from the root cutting portion 23 (excavation portion 22), and the mounting position of the soil shoveling portion 24 can be increased.

Next, the excavation operation of the seedling planting hole will be described. The first arm 8 and the second arm 9 are vertically swung according to the angle (tilt angle) of the ground with respect to the horizontal, and the hole excavator 2
, The hole excavator 2 (axis 60) is perpendicular to the ground. The rotary drive unit 21 rotationally drives the excavation unit 22, the root cutting unit 23, and the earth discharging unit 24 to swing the first arm 8 and the second arm 9 downward to sequentially move the hole excavator 2 downward.

As a result, as shown in FIG.
The excavating blade 61 cuts the soil, moves the scraped soil upward, and discharges it to excavate a cup-shaped hole B in the stratum surface. The root of the vegetation on the inner peripheral surface of the excavated hole B is arcuate cutting edge 6 of the root cutting portion 23.
The root is cut into a circular plane shape at 7 to form a seedling planting hole C. The soil moved to the ground surface is the displacement plate 7 of the soil displacement unit 24.
At 0, it is pushed away from the edge of the hole and the edge of the hole becomes flat without soil. Thereby, when the seedlings put in the pot are put into the seedling planting holes C, the excavated soil is easy to enter without disturbing, and the excavated soil does not enter the seedling planting holes C. The above-mentioned pot is a material that rots underground.

[Brief description of drawings]

FIG. 1 is a side view of a self-propelled seedling planting hole excavator showing an embodiment of the present invention.

FIG. 2 is an enlarged side view of the hole excavator.

FIG. 3 is a detailed cross-sectional view of a hydraulic motor and a speed reducer.

FIG. 4 is a side view showing a state in which an excavation portion, a root cutting portion, and a soil displacement portion are separated.

5 is a cross-sectional view taken along line EE of FIG.

FIG. 6 is an explanatory diagram of a drilling operation of a seedling planting hole.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Work vehicle, 2 ... Hole excavator, 6 ... Upper swing body, 7 ... Work machine arm, 20 ... Attachment part, 21 ... Rotation drive part, 22 ...
Excavation part, 23 ... Root cutting part, 24 ... Soil displacement part, 30 ...
Hydraulic motor, 31 ... Reducer, 32 ... Rotating body, 33 ... Shaft connecting part, 40 ... Hydraulic motor main body, 41 ... Mounting flange,
42 ... Output shaft, 43 ... Cylindrical body (output side of reduction gear), 44 ...
Mounting flange, 46 ... Input shaft (input side of reduction gear), 6
0 ... Shaft, 61 ... Excavation blade, 65 ... Cylindrical body, 67 ... Arc cutting edge, 69 ... Cylindrical body, 70 ... Displacement plate, 72 ... Joint tubular body.

Continued front page    F-term (reference) 2D012 DA00                 2D029 CA04 CB01 CC02 CD03                 2D044 DA25

Claims (4)

[Claims] 1. An excavation section (22) for rotating and scraping soil, discharging the scraped soil, and forming a cup-shaped hole in a stratum surface.
And the root cutting part that cuts the roots of the plant on the inner surface of the hole (2
The hole excavator (2) having 3) is mounted on the working machine arm (7) installed on the upper swing body (6) swingably mounted on the upper part of the traveling body (3) so as to be lifted up and down. A self-propelled seedling planting hole excavator. 2. The hole excavator (2) comprises a working machine arm (7).
And a rotary drive part (21) that is integrally combined with the mount part (20) and that drives the excavation part (22) and the root cutting part (23) to rotate. The self-propelled seedling planting hole excavator according to claim 1, wherein the (21), the excavating part (22) and the root cutting part (23) can be separated and connected. 3. The attachment part (20) is a work machine arm (7).
And a tilt link (14), and the rotation drive part (21) is concentrically connected to the hydraulic motor (30) mounted on the mounting part (20) and its output shaft (42). And a connecting portion (33) for connecting the excavating portion (22) at a position concentric with the output shaft (42) of the rotating body (32). Item 2. A self-propelled seedling planting hole excavator according to Item 2. 4. The excavation part (22) has a shape in which a spiral excavation blade (61) is fixed to the tip part of a shaft (60), and the shaft (60) is a connecting part (33) of a rotating body (32). ), The root cutting part (23) has a shape that is fitted into the shaft (60) so that it can be pulled out freely, and the root cutting part (23) is attached to the excavating blade (61) and the root cutting part of the shaft (60). The self-propelled seedling planting hole excavator according to claim 3, wherein a joint cylinder (72) can be detachably fitted to the (23).