CN112460991A

CN112460991A - Complete device of high-power direct-current heating furnace

Info

Publication number: CN112460991A
Application number: CN202011211866.9A
Authority: CN
Inventors: 易江萍; 杜昌红; 罗胜龙; 张元�
Original assignee: Guizhou Jinyuan Manganese Industry Co ltd
Current assignee: Guizhou Jinyuan Manganese Industry Co ltd
Priority date: 2020-11-03
Filing date: 2020-11-03
Publication date: 2021-03-09
Anticipated expiration: 2040-11-03
Also published as: CN112460991B

Abstract

The invention provides a high-power direct-current heating furnace complete device, relates to the technical field of smelting equipment, and aims to solve a series of problems that if a certain amount of powder and crushed aggregates are mixed in a raw material of a submerged arc furnace, the furnace condition is not smooth, the material is broken by a fire, the material intake is obviously slowed down, the waste gas and dust are increased, and the like, and the problem that the material is accumulated by stacking in a conventional feeding mode easily; the upper end of the mounting rack is fixedly provided with a vertical furnace body, and the upper end and the lower end of the furnace body are both in an isosceles trapezoid structure; the upper end of the furnace body is fixedly provided with a filtering mechanism; and a feeding mechanism is fixedly installed at the left end of the filtering mechanism. In the invention, the material block feeding box with the upper end aligned with the filter screen plate is vertically and fixedly arranged on the side wall of the right end of the inner cavity of the filter mechanism, so that a series of problems of unsmooth furnace condition, material dropping due to fire, obvious slow feeding, increased waste gas and dust and the like caused by powder and crushed materials can be solved.

Description

Complete device of high-power direct-current heating furnace

Technical Field

The invention relates to the technical field of smelting equipment, in particular to a complete device of a high-power direct-current heating furnace.

Background

The traditional direct-current submerged arc furnace mostly adopts a fixed anode mode to supply power, namely, a cathode is arranged above an anode, heat is only longitudinally transferred from top to bottom, and the area of heat radiation is small.

If a certain amount of powder and crushed aggregates are mixed in the raw materials of the ore-smelting closed furnace, the furnace condition is unsmooth, the problems of rush fire and material collapse, the material intake is obviously slowed down, the waste gas and dust are increased and the like can be caused, the problem of material accumulation can be easily caused in the conventional feeding mode, in addition, when the electrolysis is carried out in the furnace, the traditional lifting device can only lift the electrode part, the electrode can be repeatedly moved in the material body for a long time, and the materials with different hardness degrees have larger abrasion to the electrode.

Therefore, in view of the above, research and improvement are made for the existing structure and defects, and a complete set of high-power dc furnace is provided in order to achieve the purpose of higher practical value.

Disclosure of Invention

In order to solve the technical problems, the invention provides a complete device of a high-power direct-current heating furnace, which aims to solve a series of problems that if a certain amount of powder and crushed aggregates are mixed in a raw material of a submerged arc furnace, the furnace condition is not smooth, the material is suddenly burned and collapsed, the material intake is obviously slowed down, the waste gas and dust are increased, and the like, and the conventional feeding mode is easy to cause material accumulation.

The purpose and the effect of the high-power direct-current heating furnace complete device are achieved by the following specific technical means:

a high-power direct-current heating furnace complete device comprises an installation frame; the upper end of the mounting rack is fixedly provided with a vertical furnace body, and the upper end and the lower end of the furnace body are both in an isosceles trapezoid structure; the upper end of the furnace body is fixedly provided with a filtering mechanism; a feeding mechanism is fixedly arranged at the left end of the filtering mechanism; and an electrode lifting mechanism is longitudinally arranged in the middle of the furnace body.

Further, the mounting bracket includes the grudging post and connects the material platform, the planar left end edge department of mounting bracket top fixed mounting that makes progress perpendicularly has the grudging post, and the planar middle part fixed mounting in mounting bracket top has horizontal material platform that connects, and it connects the high right-hand member of top plane left end of material platform to be low.

Further, the furnace body includes that the bottom plate divides the material post and the unloading pipe, fixed mounting has the semi-cylindrical bottom plate branch material post of middle part epirelief on the bottom plane of furnace body inner chamber, and the bottom plate divides the furnace body curb plate middle part of the material post left and right sides to lean out respectively perpendicularly and is provided with the unloading pipe.

Further, the feeding mechanism comprises a feeding motor, a feeding hole, a driving screw rod, a feeding propeller and a bevel gear disc, the bottom of the left end of the feeding mechanism is vertically and fixedly provided with the feeding motor, the upper end of a feeding motor is rotationally connected with a driving screw rod through a coupler, the upper end of the driving screw rod is rotationally arranged on the side wall of the left end of a feeding mechanism through a bearing ring, the bottom of the inner cavity of the feeding mechanism is transversely rotationally provided with two feeding propellers, the right end of the feeding screw propeller is rotatably arranged on the side wall of the right end of the inner cavity of the filtering mechanism, the left end of the feeding screw propeller penetrates through the side wall of the left end of the feeding mechanism and is fixedly provided with a bevel gear plate, the front bevel gear plate and the rear bevel gear plate are both meshed with the positions of the bevel gear grooves of the driving screw rod, the upper end of the feeding mechanism is fixedly provided with a feeding hole which is wide at the upper part and narrow at the lower part, and the bottom of the inner cavity of the feeding mechanism is of a groove structure which is transversely matched with the feeding propeller.

Furthermore, the filtering mechanism comprises a filtering screen plate and a material block feeding box, a corresponding arc-shaped filtering screen plate is fixedly installed at a position, butted with the bottom of the feeding mechanism, in an inner cavity of the filtering mechanism, a material block feeding box with the upper end aligned with the filtering screen plate is vertically and fixedly installed at the position of the side wall of the right end of the inner cavity of the filtering mechanism, and the edge of the right end of the lower end of the material block feeding box is flush with the edge of the right end of the opening at the upper end of the furnace body.

Further, the electrode lifting mechanism comprises gear plates, transverse rods, guide rail rods, scraping rods, electrodes, stirring rods and a shifting plate, wherein the part of the electrode lifting mechanism, which is positioned on the outer side of the side wall of the front end of the furnace body, is an external transmission motor set, eight gear plates which are symmetrically arranged up and down are rotatably arranged on the side wall of the front end of the inner cavity of the furnace body and the side wall of the rear end of the inner cavity of the furnace body at positions corresponding to the external transmission motor set, the upper gear plate and the lower gear plate are mutually meshed, the gear plate above the left end of the electrode lifting mechanism is rotatably connected with the external transmission motor set through a rotating shaft, the edge positions between the front gear plate and the rear gear plate are respectively rotatably connected with the transverse rods through the rotating shaft, the outer end side wall of the transverse rod at the upper end is vertically and downwards fixedly provided with the two guide rail rods, the guide rail rods are in sliding sleeve, an electrode is vertically and fixedly installed in the middle of the side wall of the outer end of the shifting plate, the electrode is connected with the cross rod at the lower end in a sliding mode through a sleeve block, semicircular arc-shaped scraping rods which are evenly spaced up and down are fixedly installed between the outer ends of the front guide rail rod and the rear guide rail rod, stirring rods are vertically and downwardly fixedly installed on the side wall of the inner end of the cross rod at the upper end respectively, and the lower end of each stirring rod is connected with the cross rod at the lower end.

Compared with the prior art, the invention has the following beneficial effects:

1. because the vertical fixed mounting in filter mechanism inner chamber right-hand member lateral wall position has the upper end to throw into the case with the material piece that filter screen board was aligned mutually, the material piece is thrown into the right-hand member border of case lower extreme and furnace body upper end open-ended right-hand member border looks parallel and level mutually, when the material was carried to filter screen board department by the pay-off screw, filter through filter screen board for accessible powder and fragment fall into furnace body left side lateral wall department below, and slide down to the material platform of below and carry out centralized processing thereupon, but the impassable material piece then enters into the furnace body and carries out electrolytic treatment, can solve because powder and crushed aggregates, then can cause the furnace condition not in order, the material is collapsed to the appearance of stabbing fire, eat a series of problems such as material obviously slowed down.

2. Because the semicircular arc-shaped scraping rods with uniform upper and lower intervals are fixedly installed between the outer ends of the front and the rear guide rail rods, the stirring rods are respectively and vertically and fixedly installed downwards on the side walls of the inner ends of the transverse rods at the upper ends, the lower ends of the stirring rods are connected with the transverse rods at the lower ends in a sliding manner, after the electrode lifting mechanism is started, the gear disc rotates, so that the transverse rods between the gear discs perform annular motion along the circumference of the gear disc, and can drive the electrodes, the scraping rods, the stirring rods and the shifting plate part to reciprocate up and down, thereby carrying out different levels of electrolysis while stirring and mixing, improving the electrolysis efficiency and accelerating the liquefaction speed.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a front right upper axial view of the present invention.

Fig. 2 is a schematic diagram of the left rear upper axial view structure of the invention.

Fig. 3 is a schematic top view of the present invention.

Fig. 4 is a schematic sectional view of the position a-a in fig. 3 according to the present invention.

Fig. 5 is a schematic perspective view of the feed mechanism and the filter mechanism of the present invention in a partially disassembled state.

Fig. 6 is a schematic axial view of the feed mechanism and the filter mechanism of the present invention in a partially disassembled state.

FIG. 7 is a schematic axial view of the furnace body in a disassembled state.

Fig. 8 is a partial axial view structural schematic diagram of the electrode lifting mechanism of the present invention.

In the drawings, the corresponding relationship between the component names and the reference numbers is as follows:

1. a mounting frame; 101. erecting a frame; 102. a receiving platform; 2. a furnace body; 201. a bottom plate distribution column; 202. a discharging pipe; 3. a feeding mechanism; 301. a feeding motor; 302. a feed inlet; 303. driving the screw rod; 304. a feeding propeller; 305. a bevel gear plate; 4. a filtering mechanism; 401. a filter screen plate; 402. feeding the material block into a box; 5. an electrode lifting mechanism; 501. a gear plate; 502. a cross bar; 503. a guide rail rod; 504. a scraping rod; 505. an electrode; 506. a stirring rod; 507. and (5) dialing a plate.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In the description of the present invention, "a plurality" means two or more unless otherwise specified; the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example (b):

as shown in figures 1 to 8:

the invention provides a high-power direct-current heating furnace complete device which comprises an installation rack 1; the upper end of the mounting rack 1 is fixedly provided with a vertical furnace body 2, and the upper end and the lower end of the furnace body 2 are both in an isosceles trapezoid structure; the upper end of the furnace body 2 is fixedly provided with a filtering mechanism 4; the left end of the filtering mechanism 4 is fixedly provided with a feeding mechanism 3; the middle part of the furnace body 2 is longitudinally provided with an electrode lifting mechanism 5; furnace body 2 includes that the bottom plate divides material post 201 and unloading pipe 202, and fixed mounting has the semi-cylindrical bottom plate branch material post 201 of middle part epirelief on the bottom plane of 2 inner chambers of furnace body, can make the material assemble to the bottom left and right sides after taking place reactions such as reduction, electrolysis, is convenient for arrange outward, and the bottom plate divides 2 curb plate middle parts of furnace body of the left and right sides of material post 201 to lean out perpendicularly respectively and is provided with unloading pipe 202, can make the material draw forth outer row smoothly.

The mounting rack 1 comprises a vertical frame 101 and a material receiving platform 102, the vertical frame 101 is vertically and upwards fixedly mounted at the edge of the left end of the top plane of the mounting rack 1, the transverse material receiving platform 102 is fixedly mounted in the middle of the top plane of the mounting rack 1, and the left end of the top plane of the material receiving platform 102 is high and the right end of the top plane of the material receiving platform 102 is low.

Wherein, the feeding mechanism 3 comprises a feeding motor 301, a feeding port 302, a driving screw 303, a feeding screw 304 and a helical gear disc 305, the bottom of the left end of the feeding mechanism 3 is vertically and fixedly provided with the feeding motor 301, the upper end of the feeding motor 301 is rotatably connected with the driving screw 303 through a coupling, the upper end of the driving screw 303 is rotatably arranged on the side wall of the left end of the feeding mechanism 3 through a bearing ring, the bottom of the inner cavity of the feeding mechanism 3 is transversely and rotatably provided with two feeding screws 304, the right end of the feeding screw 304 is rotatably arranged on the side wall of the right end of the inner cavity of the filtering mechanism 4, the left end of the feeding screw 304 penetrates through the side wall of the left end of the feeding mechanism 3 to be fixedly provided with the helical gear disc 305, the front and the rear helical gear discs 305 are all engaged with the helical gear groove of the driving screw 303, the upper, and the inner chamber bottom of feed mechanism 3 is then for horizontal and the groove structure that the pay-off screw 304 suits, when feeding motor 301 drives, makes drive lead screw 303 rotatory to make the helical gear dish 305 who meshes with drive lead screw 30 rotate, it is rotatory to drive pay-off screw 304, makes the material carry from a left side to the right side, but the equal volume in order is carried, avoids the material to pile up the problem appearance that too much be convenient for the screening.

Wherein, the filtering mechanism 4 comprises a filtering screen plate 401 and a material block feeding box 402, a corresponding arc-shaped filtering screen plate 401 is fixedly arranged at the position in the inner cavity of the filtering mechanism 4, which is butted with the bottom of the feeding mechanism 3, a material block feeding box 402 with the upper end aligned with the filtering screen plate 401 is vertically and fixedly arranged at the position of the side wall at the right end of the inner cavity of the filtering mechanism 4, the right end edge at the lower end of the material block feeding box 402 is flush with the right end edge of the upper end opening of the furnace body 2, when the material is conveyed to the position of the filtering screen plate 401 by the feeding screw 304, the material is filtered by the filtering screen plate 401, so that the passing powder and the fragments fall into the left end side wall of the furnace body 2 below and slide down to the material receiving platform 102 at the lowest part for centralized treatment, while the non-passing material blocks enter the furnace body 2 for electrolytic treatment, thereby solving the problems that the furnace condition is, the feed intake is obviously slowed down, the waste gas and dust are increased, and the like.

Wherein, the electrode lifting mechanism 5 comprises a gear plate 501, a cross bar 502, guide rail rods 503, a scraping rod 504, an electrode 505, a stirring rod 506 and a shifting plate 507, the part of the electrode lifting mechanism 5 positioned at the outer side of the side wall of the front end of the furnace body 2 is an external transmission motor set, eight gear plates 501 which are symmetrically arranged up and down are rotatably arranged at the positions corresponding to the external transmission motor set on the side wall of the front end and the side wall of the rear end of the inner cavity of the furnace body 2, the upper gear plate 501 and the lower gear plate 501 are mutually engaged, the gear plate 501 above the left end is rotatably connected with the external transmission motor set through a rotating shaft, the edge positions between the front gear plate 501 and the rear gear plate are respectively rotatably connected with the cross bar 502 through the rotating shaft, two guide rail rods 503 are vertically and downwardly fixedly arranged on the side wall of the outer end of the cross bar 502 at the upper end, the guide rail rods 503 are slidably sleeved with the cross bar 502 at the lower, an electrode 505 is vertically and fixedly installed in the middle of the side wall of the outer end of the shifting plate 507, the electrode 505 is connected with the cross rod 502 at the lower end in a sliding mode through a sleeve block, semicircular arc-shaped scraping rods 504 which are uniformly spaced up and down are fixedly installed between the outer ends of the front guide rail rod 503 and the rear guide rail rod 503, stirring rods 506 are respectively and vertically and fixedly installed on the side wall of the inner end of the cross rod 502 at the upper end downwards, the lower ends of the stirring rods 506 are connected with the cross rod 502 at the lower end in a sliding mode, after the electrode lifting mechanism 5 is started, the gear disc 501 rotates, the cross rod 502 between the gear discs 501 performs annular motion along the circumference of the gear disc 501, and the electrode 505, the scraping rods 504, the stirring rods 506 and the shifting plate 507 can be driven to reciprocate.

The specific use mode and function of the embodiment are as follows:

in the using process, when the feeding motor 301 is driven, the driving screw rod 303 is rotated, so that the bevel wheel disc 305 engaged with the driving screw rod 30 is rotated to drive the feeding screw propeller 304 to rotate, so that the materials are conveyed from left to right and can be conveyed in an orderly and uniform manner, the problem that the materials are accumulated too much and are not convenient for screening is avoided, because the proper arc-shaped filter screen plate 401 is fixedly arranged at the position in the inner cavity of the filter mechanism 4, which is butted with the bottom of the feeding mechanism 3, the material block feeding box 402 with the upper end aligned with the filter screen plate 401 is vertically and fixedly arranged at the position of the side wall at the right end of the inner cavity of the filter mechanism 4, the right end edge at the lower end of the material block feeding box 402 is flush with the right end edge of the opening at the upper end of the furnace body 2, when the materials are conveyed to the filter screen plate 401 by the feeding screw propeller 304, the materials are, and then slide down to the lowest receiving platform 102 for centralized treatment, while the impassable material blocks enter into the furnace body 2 for electrolytic treatment, so as to solve a series of problems of unsmooth furnace conditions, rush and material collapse, obvious slow material consumption, increased waste gas and dust, etc. when the material blocks enter into the furnace body 2, semi-arc shaped scraping rods 504 with uniform up-down intervals are fixedly arranged between the outer ends of the front and rear guide rail rods 503, stirring rods 506 are respectively and vertically and downwardly fixedly arranged on the inner side walls of the cross rods 502 at the upper end, the lower ends of the stirring rods 506 are connected with the cross rods 502 at the lower end in a sliding manner, when the electrode lifting mechanism 5 is started, the gear plate 501 rotates, so that the cross rods 502 between the gear plates 501 perform circular motion along the circumference of the gear plate 501, and can drive the electrodes 505, the scraping rods 504, the stirring rods 506 and the shifting plate 507 to reciprocate up and down, thereby can carry out the electrolysis of different levels when the stirring is mixed, the electrolysis efficiency has been improved, the liquefaction speed has been accelerated, and fixed mounting has the semi-cylindrical's of middle part epirelief bottom plate branch stub 201 on the bottom plane of furnace body 2 inner chambers, can make the material take place reduction, the electrolysis waits to assemble to the bottom left and right sides after the reaction, be convenient for arrange outward, the bottom plate divides 2 curb plate middle parts of furnace body of stub 201 left and right sides to lean out perpendicularly respectively and is provided with unloading pipe 202, can make the material draw forth outer row smoothly.

The embodiments of the present invention have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A high-power direct-current heating furnace complete equipment is characterized in that: comprises a mounting frame (1); the upper end of the mounting rack (1) is fixedly provided with a vertical furnace body (2), and the upper end and the lower end of the furnace body (2) are both of isosceles trapezoid structures; the upper end of the furnace body (2) is fixedly provided with a filtering mechanism (4); a feeding mechanism (3) is fixedly arranged at the left end of the filtering mechanism (4); an electrode lifting mechanism (5) is longitudinally arranged in the middle of the furnace body (2); the feeding mechanism (3) comprises a feeding motor (301), a driving screw rod (303), a feeding propeller (304) and a helical gear disc (305), a feeding motor (301) is vertically and fixedly arranged at the bottom of the left end of the feeding mechanism (3), the upper end of a feeding motor (301) is rotationally connected with a driving screw rod (303) through a coupler, the upper end of the driving screw rod (303) is rotationally arranged on the left end side wall of a feeding mechanism (3) through a bearing ring, the bottom of the inner cavity of the feeding mechanism (3) is laterally rotationally provided with two feeding screw propellers (304), the right end of the feeding propeller (304) is rotatably arranged on the right end side wall of the inner cavity of the filtering mechanism (4), the left end of the feeding propeller (304) penetrates through the side wall of the left end of the feeding mechanism (3) and is fixedly provided with a bevel gear plate (305), and the front and the rear bevel gear plates (305) are meshed with the positions of the bevel gear grooves of the driving screw rod (303).

2. The high power dc furnace plant of claim 1, wherein: mounting bracket (1) include grudging post (101) and connect material platform (102), the planar left end edge department of mounting bracket (1) top fixed mounting that makes progress perpendicularly has grudging post (101), and mounting bracket (1) top planar middle part fixed mounting has horizontal material platform (102) that connects, and its high right-hand member in top plane left end that connects material platform (102) is low.

3. The high power dc furnace plant of claim 1, wherein: furnace body (2) divide stub bar (201) and unloading pipe (202) including the bottom plate, fixed mounting has the semi-cylindrical bottom plate of middle part epirelief to divide stub bar (201) on the bottom plane of furnace body (2) inner chamber, and furnace body (2) curb plate middle part that the bottom plate divides stub bar (201) left and right sides is provided with unloading pipe (202) in the slope perpendicularly respectively.

4. The high power dc furnace plant of claim 1, wherein: the feeding mechanism (3) further comprises a feeding hole (302), the feeding hole (302) with a wide upper part and a narrow lower part is fixedly arranged at the upper end of the feeding mechanism (3), and the bottom of an inner cavity of the feeding mechanism (3) is of a groove structure which is transversely matched with the feeding propeller (304).

5. The high power dc furnace plant of claim 1, wherein: the filter mechanism (4) comprises a filter screen plate (401) and a material block feeding box (402), wherein the adaptive arc-shaped filter screen plate (401) is fixedly installed at the position, butted with the bottom of the feeding mechanism (3), in the inner cavity of the filter mechanism (4), the material block feeding box (402) with the upper end aligned with the filter screen plate (401) is vertically and fixedly installed at the position of the side wall of the right end of the inner cavity of the filter mechanism (4), and the right end edge of the lower end of the material block feeding box (402) is aligned with the right end edge of the upper end opening of the furnace body (2).

6. The high power dc furnace plant of claim 1, wherein: electrode elevating system (5) are including toothed disc (501) and horizontal pole (502), the part that electrode elevating system (5) are located furnace body (2) front end lateral wall outside is external transmission motor group, furnace body (2) inner chamber front end lateral wall and rear end lateral wall on with the corresponding position department rotation of external transmission motor group install eight gear disc (501) of up-down symmetrical arrangement, and intermeshing between two upper and lower gear disc (501), be connected through the pivot rotation between gear disc (501) of its left end top and the external transmission motor group, border position department between two relative gear disc (501) is connected with horizontal pole (502) through the pivot rotation respectively around.

7. The high power dc furnace plant of claim 6, wherein: electrode elevating system (5) still include guide rail pole (503), electrode (505) and dial board (507), the upper end perpendicular downward fixed mounting has two guide rail poles (503) on the outer end lateral wall of horizontal pole (502), and its guide rail pole (503) cup joints with horizontal pole (502) of lower extreme mutually that slide, and fixed mounting has the lower extreme to dial board (507) for the point taper between the lower extreme of two guide rail poles (503), dial the vertical fixed mounting in middle part of board (507) outer end lateral wall and have electrode (505), be connected through the cover block slip between horizontal pole (502) of its electrode (505) and the lower extreme.

8. The high power dc furnace plant of claim 7, wherein: the electrode lifting mechanism (5) further comprises a scraping rod (504) and a stirring rod (506), wherein the front and the back are fixedly provided with the semi-arc scraping rod (504) which is uniformly arranged at an upper and lower interval between the outer ends of the guide rail rods (503), the inner end side walls of the cross rods (502) at the upper end are respectively and vertically and downwards fixedly provided with the stirring rod (506), and the lower ends of the stirring rods (506) are connected with the cross rods (502) at the lower end in a sliding manner.