Explosive filling device for blasting in frozen soil area

Abstract

The utility model discloses an explosive filling device for blasting in a frozen soil area, which comprises an explosive adding cylinder with an explosive adding port at the top and an explosive outlet at the bottom, a sliding sleeve is sleeved outside the explosive adding cylinder along the axial direction in a sliding manner, a plurality of positioning pieces are uniformly arranged outside the explosive adding cylinder along the circumferential direction, and the positioning pieces can move along the radial direction of the explosive adding cylinder; a first inclined surface is arranged at the top of the positioning piece, a second inclined surface which is matched with the first inclined surface for extrusion is arranged at the bottom of the sliding sleeve, and an axial pushing device is arranged at the top of the sliding sleeve; the bottom end of the positioning piece is provided with a blocking piece which extends into the medicine adding cylinder and shields a medicine outlet of the medicine adding cylinder, and a spiral medicine feeding device is arranged in the medicine adding cylinder. In the explosive filling process, the stability of the whole filling device can be guaranteed, automatic reset is achieved after explosive filling is completed, the explosive outlet is closed, and loss of redundant explosives is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of blasting explosive filling, and relates to an explosive filling device for blasting in frozen soil areas. Background Art

[0002] During the exploitation of iron ore and magnetite in high-altitude areas, due to the low temperature, the moisture in the ore-bearing rock strata or soil freezes, forming frozen rock or frozen soil. Since frozen rock and frozen soil are tougher and harder than ordinary rock masses, it is difficult to efficiently break frozen rock and frozen soil layers by traditional drilling and excavation methods. In the prior art, during the exploitation of iron ore and magnetite in high-altitude areas, the frozen rock and frozen soil are generally broken by drilling and blasting, that is, small-diameter deep holes are drilled in the frozen rock and frozen soil layers, and explosives are filled in the deep holes, and the frozen rock and frozen soil are broken by blasting.

[0003] However, in the existing explosive filling process, usually a hollow dosing cylinder or dosing rod is placed inside the blasting hole, and then explosives are filled into the blasting hole through the dosing cylinder or dosing rod. Due to the lack of an effective positioning and fixing structure in the existing dosing cylinder or dosing rod, the stability of the dosing cylinder or dosing rod during the explosive filling process is insufficient, which in turn affects the accuracy and efficiency of explosive filling. At the same time, the medicine outlet of the existing dosing cylinder or dosing rod is in an open state all the time. After the explosive filling is completed, when the dosing cylinder or dosing rod is taken out of the blasting hole, there will be leakage of excess explosives, which also leads to deviation in the amount of explosive filling and causes loss and waste of explosives.

[0004] Therefore, in view of the above technical problems existing in the existing dosing cylinders and dosing rods for frozen soil, the utility model discloses an explosive filling device for blasting in frozen soil areas. Summary of the Utility Model

[0005] The purpose of the utility model is to provide an explosive filling device for blasting in frozen soil areas, which can ensure the stability of the whole filling device during the explosive filling process, and automatically reset and close the medicine outlet after the explosive filling is completed to avoid loss of excess explosives.

[0006] The utility model is realized by the following technical solutions:

[0007] An explosive loading device for blasting in frozen soil areas, comprising a medicine adding cylinder with a medicine adding port at the top and a medicine outlet at the bottom. A sliding sleeve is sleeved on the outside of the medicine adding cylinder and can slide axially. A number of positioning members are evenly arranged circumferentially on the outside of the medicine adding cylinder, and the positioning members can move radially along the medicine adding cylinder. A first inclined surface is arranged at the top of the positioning member, and a second inclined surface that cooperates with and squeezes the first inclined surface is arranged at the bottom of the sliding sleeve. An axial pushing device is arranged at the top of the sliding sleeve. A baffle is arranged at the bottom end of the positioning member and extends into the medicine adding cylinder to block the medicine outlet of the medicine adding cylinder. A spiral medicine feeding device is arranged inside the medicine adding cylinder.

[0008] The sliding seat is pushed downward by the axial pushing device, so that the second inclined surface at the bottom of the sliding seat squeezes the first inclined surface at the top of the positioning member, forcing the positioning member to slide and expand radially along the medicine adding cylinder, enabling the positioning member to expand and be clamped at the orifice of the blasting hole, thereby ensuring the stability during the explosive loading process. At the same time, during the radial sliding and expansion of the positioning member, the baffle at the bottom of the positioning member opens the medicine outlet at the bottom of the medicine adding cylinder. Explosives are added into the inside of the medicine adding cylinder through the medicine adding port of the medicine adding cylinder, and at the same time, the explosives inside the medicine adding cylinder are spirally conveyed to the medicine outlet by the rotation of the spiral medicine feeding device, and then the explosives are evenly and smoothly loaded into the blasting hole.

[0009] To better implement the present utility model, further, an installation disk is sleeved on the outside of the medicine adding cylinder at a position below the sliding sleeve. A number of radial sliding grooves are evenly arranged at intervals circumferentially on the installation disk, and the middle position of the positioning member is slidably connected with the radial sliding grooves in a matching manner.

[0010] To better implement the present utility model, further, the positioning member comprises an L-shaped limiting member, a sliding seat, a connecting member, and a radial reset spring. The sliding seat is slidably connected with the radial sliding grooves in a matching manner. An L-shaped limiting member is arranged at the top of the sliding seat, and a first inclined surface is arranged at the top end of the L-shaped limiting rod. One end of the baffle is connected to the bottom of the sliding seat through a connecting member. A radial reset spring is arranged between the sliding seat and the barrel wall of the medicine adding cylinder.

[0011] To better implement the present utility model, further, the axial pushing device comprises an installation bracket, a pushing ring, a jack, and an axial reset spring. The installation bracket is arranged at the top of the sliding sleeve. At least one jack is arranged on the installation bracket. The pushing end of the jack extends downward and is connected with a pushing ring. The pushing ring is coaxially arranged with the sliding sleeve, and the bottom end of the pushing ring abuts against the top of the sliding sleeve. An axial reset spring is arranged between the top of the sliding sleeve and the installation bracket.

[0012] To better implement the present utility model, further, an axial guiding column is further included. The axial guiding column is arranged on the mounting bracket parallel to the axis of the medicine adding cylinder, and a guiding hole slidably engaged with the axial guiding column is arranged on the pushing ring.

[0013] To better implement the present utility model, further, the spiral medicine feeding device includes a rotating shaft, a spiral blade, and a dispersing column. The rotating shaft is coaxially and rotatably arranged inside the medicine adding cylinder, and a dispersing column and a spiral blade are sequentially arranged on the outside of the rotating shaft from top to bottom.

[0014] To better implement the present utility model, further, a light shaft, a second rotating shaft, and a second spiral blade are further included. The bottom end of the rotating shaft is coaxially connected with the light shaft. The outer side of the light shaft is attached to one end of the baffle to block the medicine outlet of the medicine adding cylinder. The bottom end of the light shaft is coaxially connected with the second rotating shaft, and a second spiral blade is arranged on the outside of the second rotating shaft.

[0015] To better implement the present utility model, further, the second spiral blade is in a conical shape with diameters decreasing sequentially from top to bottom.

[0016] Compared with the prior art, the present utility model has the following advantages and beneficial effects:

[0017] In the present utility model, a sliding sleeve is axially and slidably sleeved outside the medicine adding cylinder. During the process of filling explosives, the sliding sleeve is axially pushed downward by an axial pushing device. Then, the second inclined surface at the bottom of the sliding sleeve presses the first inclined surface at the top of the positioning member, forcing the positioning member to expand and slide radially along the medicine adding cylinder until the positioning member is clamped and positioned with the opening of the blasting hole to ensure the stability of the entire explosive filling process. At the same time, during the expansion and sliding process of the positioning member, the baffle at its bottom is driven to open the medicine outlet, and the explosives are stably and evenly transported and filled into the inside of the blasting hole through the spiral medicine feeding device inside the medicine adding cylinder. After the explosives are filled, the axial pushing device retracts upward, so that the second inclined surface at the bottom of the sliding sleeve no longer presses the first inclined surface at the top of the positioning member. At this time, the positioning member slides reversely to drive the baffle to re-block and seal the medicine outlet, avoiding the leakage and loss of explosives during the process of taking out the medicine adding cylinder. Description of the Drawings

[0018] Figure 1 Schematic three-dimensional structure diagram of the explosive filling device for blasting in frozen soil areas;

[0019] Figure 2 Explosion structure diagram of the explosive filling device for blasting in frozen soil areas;

[0020] Figure 3 Cross-sectional view of the explosive filling device for blasting in frozen soil areas;

[0021] Figure 4Schematic diagram of the baffle opening the medicine outlet;

[0022] Figure 5 Schematic structural diagram of the screw medicine delivery device;

[0023] Figure 6 Schematic installation diagram of the positioning member;

[0024] Figure 7 Schematic structural diagram of the positioning member.

[0025] Wherein: 1 - medicine adding cylinder; 2 - sliding sleeve; 3 - positioning member; 4 - axial pushing device; 5 - baffle; 6 - screw medicine delivery device; 7 - mounting plate; 31 - L-shaped limiting member; 32 - sliding seat; 33 - connecting member; 34 - radial reset spring; 41 - pushing ring; 42 - jack; 43 - axial reset spring; 44 - axial guiding column; 61 - rotating shaft; 62 - screw blade; 63 - dispersing column; 64 - optical axis; 65 - second transmission shaft; 66 - second screw blade; 71 - radial sliding groove; 100 - first inclined surface; 200 - second inclined surface. Detailed implementation manners

[0026] The following detailed descriptions are all illustrative and are intended to provide further explanations of the present utility model. Unless otherwise specified, all technical and scientific terms used in the present utility model have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present utility model belongs.

[0027] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present utility model. As used herein, unless the present utility model clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] For the convenience of narration, if the words "upper", "lower", "left", and "right" appear in the present utility model, they only indicate the same directions as the upper, lower, left, and right of the attached drawings themselves, and do not limit the structure. They are only for facilitating the description of the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present utility model.

[0029] Glossary: Terms such as "installation", "connection", "linkage", and "fixation" in the present utility model should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection, a direct connection or an indirect connection through an intermediate medium, an internal connection between two components, or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] Embodiment 1:

[0031] An explosive loading device for blasting in frozen soil areas in this embodiment, as Figure 1 and Figure 2 shown, includes a dosing cylinder 1 with a dosing port at the top and a medicine outlet at the bottom. A sliding sleeve 2 is slidably sleeved on the outside of the dosing cylinder 1 along the axial direction. A plurality of positioning members 3 are evenly arranged on the outside of the dosing cylinder 1 along the circumferential direction, and the positioning members 3 can move radially along the dosing cylinder 1; a first inclined surface 100 is provided at the top of the positioning member 3, a second inclined surface 200 that cooperates with and presses the first inclined surface 100 is provided at the bottom of the sliding sleeve 2, and an axial pushing device 4 is provided at the top of the sliding sleeve 2; a baffle 5 extending into the dosing cylinder 1 and blocking the medicine outlet of the dosing cylinder 1 is provided at the bottom end of the positioning member 3, and a spiral medicine feeding device 6 is provided inside the dosing cylinder 1.

[0032] The dosing cylinder 1 is provided with a dosing port at the top and a medicine outlet at the bottom. Explosives are loaded into the dosing cylinder 1 through the dosing port. At the same time, through the rotation of the spiral medicine feeding device 6 inside the dosing cylinder 1, the explosives are spirally conveyed to the medicine outlet. When the axial pushing device 4 does not push downward, the second inclined surface 200 at the bottom of the sliding block 2 does not press the first inclined surface 100 at the top of the positioning member 3 at this time. At this time, the plurality of circumferentially arranged positioning members 3 are in a gathered state, so that the baffle 5 at the bottom of the positioning member 3 blocks the medicine outlet. At this time, the explosives inside the dosing cylinder 1 cannot flow out, avoiding the loss of explosives.

[0033] When it is necessary to load explosives, the dosing cartridge 1 is installed at the orifice of the blasting hole, and the medicine outlet of the dosing cartridge 1 extends into the interior of the blasting hole. At this time, the axial pushing device 4 pushes downward axially, and then drives the sliding seat 2 to slide downward, so that the second inclined surface 200 at the bottom of the sliding seat 2 presses against the first inclined surface 100 at the top of the positioning member 3. Under the action of the pressing force, the three circumferentially arranged positioning members 3 all slide and expand along the radial direction of the dosing cartridge 1, so that the retaining piece 5 at the bottom of the positioning member 3 no longer blocks the medicine outlet. At this time, the explosives inside the dosing cartridge 1 can be smoothly loaded into the blasting hole from the medicine outlet under the spiral feeding action of the spiral feeding device 6. At the same time, after the positioning member 3 expands, it can be clamped and positioned with the orifice of the blasting hole, thereby ensuring the stability of the entire explosive loading device and ensuring the smooth progress of the medicine adding process.

[0034] After the explosive loading is completed, the axial pushing device 4 retracts upward. At this time, the second inclined surface 200 at the bottom of the sliding sleeve 2 no longer presses against the first inclined surface 100 at the top of the positioning member 3. At this time, the entire explosive loading device can be taken out of the blasting hole through an external lifting device or hoisting device.

[0035] Embodiment 2:

[0036] An explosive loading device for blasting in frozen soil areas is improved on the basis of Embodiment 1. As Figures 2 - 4 shown, an installation disk 7 is sleeved below the sliding sleeve 2 on the outside of the dosing cartridge 1. A plurality of radial sliding grooves 71 are evenly arranged at intervals along the circumference on the installation disk 7. The middle position of the positioning member 3 is slidably connected with the radial sliding grooves 71.

[0037] Furthermore, as Figure 7 shown, the positioning member 3 includes an L-shaped limiting member 31, a sliding seat 32, a connecting member 33, and a radial return spring 34. The sliding seat 32 is slidably connected with the radial sliding grooves 71. An L-shaped limiting member 31 is arranged at the top of the sliding seat 32. The top end of the L-shaped limiting rod 31 is provided with a first inclined surface 100. One end of the retaining piece 5 is connected to the bottom of the sliding seat 32 through a connecting member 33. A radial return spring 34 is arranged between the sliding seat 32 and the barrel wall of the dosing cartridge 1.

[0038] Three radial sliding grooves 71 are evenly spaced circumferentially on the installation disk 7. Grooves that are slidably engaged with the groove walls of the radial sliding grooves 71 are provided on both sides of the sliding seat 32, thereby enabling the sliding seat 32 to slide along the radial sliding grooves 71. An L-shaped limiting member 31 is welded or fixedly connected to the top of the sliding seat 32 by bolts, and a connecting member 33 is welded or fixedly connected to the bottom of the sliding seat 32 by bolts. A second inclined surface 200 is provided on the top of the L-shaped limiting member 31 near one side of the sliding sleeve 2. When the sliding sleeve 2 is pushed downward, the first inclined surface 100 radially presses the second inclined surface 200, forcing the sliding seat 32 to slide along the radial sliding groove 71. At this time, the L-shaped limiting member 31 expands radially and slides to be clamped and positioned with the orifice of the blasting hole, and the radial return spring 34 is stretched. At the same time, the connecting member 33 drives the baffle 5 to move away from the medicine outlet to open the medicine outlet. When the sliding sleeve 2 slides upward, the second inclined surface 200 no longer presses the first inclined surface 100. At this time, the radial return spring 34 retracts and resets, driving the sliding seat 32 to slide toward the direction close to the medicine adding cylinder 1, so that the baffle 5 resets to block and close the medicine outlet again.

[0039] Other parts of this embodiment are the same as those of Embodiment 1, so they will not be described in detail.

[0040] Embodiment 3:

[0041] An explosive loading device for blasting in frozen soil areas is improved on the basis of Embodiment 1 or 2. As Figures 1 - 4 shown, the axial pushing device 4 includes an installation bracket, a pushing ring 41, a jack 42, and an axial return spring 43. The installation bracket is arranged on the top of the sliding sleeve 2. At least one jack 42 is arranged on the installation bracket. The pushing end of the jack 42 extends downward and is connected to a pushing ring 41. The pushing ring 41 is coaxially arranged with the sliding sleeve 2, and the bottom end of the pushing ring 41 abuts against the top of the sliding sleeve 2. An axial return spring 43 is arranged between the top of the sliding sleeve 2 and the installation bracket.

[0042] Furthermore, the axial pushing device 4 further includes an axial guiding column 44. The axial guiding column 44 is arranged on the installation bracket parallel to the axis of the medicine adding cylinder 1. A guiding hole that is slidably engaged with the axial guiding column 44 is arranged on the pushing ring 41.

[0043] An installation hole is provided at the center of the installation bracket. The installation hole is fixedly connected to the outer cylindrical wall of the chemical addition cylinder 1, and the chemical addition cylinder 1 is supported by the installation bracket. At least one opening or slot for installing the jack 42 is provided on the installation bracket. The pushing end of the jack 42 extends downward and is connected to the top end face inside the pushing ring 41. The bottom end face of the pushing ring 41 abuts against the top end face of the sliding sleeve 2. When the jack 42 pushes downward, the sliding sleeve 2 is evenly pushed downward through the pushing ring 41, and at the same time, the axial return spring 43 is stretched. When the pushing end of the jack 42 retracts, the pushing ring 41 no longer pushes the sliding sleeve 2 downward. At this time, the sliding sleeve 2 slides upward and resets under the reset contraction of the axial return spring 43.

[0044] Other parts of this embodiment are the same as those of Embodiment 1 or 2, so they will not be described in detail.

[0045] Embodiment 4:

[0046] An explosive loading device for blasting in frozen soil areas is improved on the basis of any one of Embodiments 1-3, as Figure 5 and Figure 6 shown. The spiral medicine feeding device 6 includes a rotating shaft 61, a spiral blade 62, and a dispersing column 63. The rotating shaft 61 is coaxially and rotatably arranged inside the chemical addition cylinder 1. The dispersing column 63 and the spiral blade 62 are sequentially arranged on the outside of the rotating shaft 61 from top to bottom.

[0047] The top end of the rotating shaft 61 extends upward to the outside of the chemical addition cylinder 1 and is sleeved with a rotating handle. The rotating shaft 61 is driven to rotate by the rotating handle, and then the explosives inside the chemical addition cylinder 1 are stirred by the rotation of the dispersing column 63 to prevent the explosives from caking. At the same time, the spiral conveying of the explosives is realized by the rotation of the spiral blade 62.

[0048] Further, the spiral medicine feeding device 6 further includes a smooth shaft 64, a second rotating shaft 65, and a second spiral blade 66. The bottom end of the rotating shaft 61 is coaxially connected to the smooth shaft 64. The outer side surface of the smooth shaft 64 is attached to one end of the baffle 5 to block the medicine outlet of the chemical addition cylinder 1. The bottom end of the smooth shaft 64 is coaxially connected to the second rotating shaft 65, and the second spiral blade 66 is arranged on the outside of the second rotating shaft 65.

[0049] The outer side surface of the smooth shaft 64 is attached and cooperatively arranged with one end of the baffle 5. When the baffle 5 blocks the medicine outlet, one end of the baffle 5 just contacts and cooperates with the outer side surface of the smooth shaft 64 to ensure that the medicine outlet is in a tightly closed state. After the baffle 5 slides radially and expands, the baffle 5 is separated from the outer side surface of the smooth shaft 64, and at this time, the medicine outlet is opened. The rotating shaft 61 drives the second rotating shaft 65 to rotate through the smooth shaft 64, and then drives the second spiral blade 66 extending into the blasting hole to rotate. The explosives are conveyed to the bottom of the blasting hole through the rotation of the second spiral blade 66 to ensure that the explosives are fully filled inside the blasting hole.

[0050] Further, the second spiral blade 66 is in a conical shape with a diameter decreasing successively from top to bottom, which can not only ensure the spiral conveyance of the explosive to the bottom of the blasting hole, but also avoid the second spiral blade 66 from excessively agitating the explosive.

[0051] Other parts of this embodiment are the same as any one of Embodiments 1-3, so they will not be described in detail herein.

[0052] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An explosive loading device for blasting in frozen soil areas, comprising a charge-adding cylinder (1) with a charge-adding port on the top and a charge-discharging port on the bottom, characterized in that: The outside of the dosing barrel (1) is provided with a sliding sleeve (2) along the axial sliding sleeve, and the outside of the dosing barrel (1) is evenly provided with a plurality of positioning members (3) along the circumferential direction, and the positioning members (3) can move along the radial direction of the dosing barrel (1); the top of the positioning member (3) is provided with a first inclined surface (100), the bottom of the sliding sleeve (2) is provided with a second inclined surface (200) that cooperates with the first inclined surface (100) for extrusion, and the top of the sliding sleeve (2) is provided with an axial pushing device (4); the bottom end of the positioning member (3) is provided with a blocking piece (5) that extends into the inside of the dosing barrel (1) and blocks the drug outlet of the dosing barrel (1), and the inside of the dosing barrel (1) is provided with a spiral drug delivery device (6).

2. The explosive charging device for blasting in frozen soil areas according to claim 1, characterized in that: The exterior of the dosing cartridge (1) is provided with a mounting plate (7) located below the sliding sleeve (2), and a plurality of radial sliding grooves (71) are evenly spaced along the circumference of the mounting plate (7), and the middle portion of the positioning member (3) is slidably connected to the radial sliding grooves (71).

3. The explosive charging device for blasting in frozen soil areas according to claim 2, characterized in that: The positioning member (3) comprises an L-shaped limit member (31), a sliding seat (32), a connecting member (33), and a radial return spring (34); the sliding seat (32) is slidably connected to the radial slide groove (71); an L-shaped limit member (31) is arranged on the top of the sliding seat (32); a first inclined surface (100) is arranged on the top of the L-shaped limit rod (31); the bottom of the sliding seat (32) is connected to one end of the baffle (5) through the connecting member (33); a radial return spring (34) is arranged between the sliding seat (32) and the wall of the dosing cartridge (1).

4. The explosive charging device for blasting in frozen soil areas according to any one of claims 1 to 3, characterized in that: The axial thrust device (4) comprises a mounting bracket, a thrust ring (41), a jack (42), and an axial return spring (43); the mounting bracket is arranged at the top of the sliding sleeve (2); at least one jack (42) is arranged on the mounting bracket; the thrust end of the jack (42) extends downward and is connected to the thrust ring (41); the thrust ring (41) is coaxially arranged with the sliding sleeve (2), and the bottom end of the thrust ring (41) abuts against the top of the sliding sleeve (2); an axial return spring (43) is arranged between the top of the sliding sleeve (2) and the mounting bracket.

5. The explosive charging device for blasting in frozen soil areas according to claim 4, characterized in that: It also includes an axial guide column (44), which is arranged on the mounting bracket parallel to the axis of the dosing cartridge (1), and the push ring (41) is provided with a guide hole that is slidably connected to the axial guide column (44).

6. An explosive charging device for blasting in frozen soil areas according to any one of claims 1 to 3, characterized in that: The spiral medicine delivery device (6) comprises a rotating shaft (61), a spiral blade (62), and a scattering column (63); the rotating shaft (61) is coaxially rotatably arranged inside the medicine adding barrel (1); and the scattering column (63) and the spiral blade (62) are arranged on the outside of the rotating shaft (61) in sequence from top to bottom.

7. The explosive charging device for blasting in frozen soil areas according to claim 6, characterized in that: It also includes an optical axis (64), a second rotating axis (65), and a second spiral blade (66); the bottom end of the rotating axis (61) is coaxially connected to the optical axis (64); the outer side surface of the optical axis (64) is in contact with one end of the blocking piece (5) to block the drug outlet of the drug adding cartridge (1); the bottom end of the optical axis (64) is coaxially connected to the second rotating axis (65); and a second spiral blade (66) is arranged on the outer side of the second rotating axis (65).

8. The explosive charging device for blasting in frozen soil areas according to claim 7, characterized in that: The second spiral blade (66) is in a tapered shape with a diameter decreasing from top to bottom.

Images