CN110902542A

CN110902542A - Coal mine vertical shaft lifting system and anti-resonance derrick thereof

Info

Publication number: CN110902542A
Application number: CN201911215848.5A
Authority: CN
Inventors: 刘跃; 索双富; 时剑文
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2019-12-02
Filing date: 2019-12-02
Publication date: 2020-03-24
Anticipated expiration: 2039-12-02
Also published as: CN110902542B

Abstract

The invention relates to the technical field of coal mine vertical shaft hoisting systems, and particularly provides a coal mine vertical shaft hoisting system and an anti-resonance derrick thereof, aiming at solving the problems that the existing coal mine vertical shaft hoisting system is easy to resonate in the operation process and has larger potential safety hazard. For the purpose, the derrick comprises a first upright column, a second upright column, a third upright column and a fourth upright column, wherein adjacent two of the first upright column, the second upright column, the third upright column and the fourth upright column are connected through an upper cross beam and a lower cross beam; a first crown wheel mounting position is arranged between the upper parts of the first upright post and the fourth upright post, and a second crown wheel mounting position is arranged between the upper parts of the second upright post and the third upright post; a first inclined strut assembly is arranged at a position below the lower cross beam between the first upright column and the second upright column, and/or a first inclined strut assembly is arranged at a position below the lower cross beam between the third upright column and the fourth upright column. By such an arrangement, the natural frequency of the mast is changed, reducing the risk of resonance.

Description

Coal mine vertical shaft lifting system and anti-resonance derrick thereof

Technical Field

The invention relates to the technical field of coal mine vertical shaft hoisting systems, and particularly provides a coal mine vertical shaft hoisting system and an anti-resonance derrick thereof.

Background

In coal mining sites, coal mine vertical shaft hoisting systems are mainly used for transporting coal at the bottom of a vertical shaft to the outside of the shaft. As shown in fig. 1 and 2, the conventional coal mine shaft hoisting system mainly includes a derrick 1 disposed over a wellhead 6, the derrick 1 includes a first vertical column 111, a second vertical column 112, a third vertical column 113 and a fourth vertical column 114, and the first vertical column 111 and the second vertical column 112 are connected by a first upper cross member 121 and a first lower cross member 131. The second upright 112 and the third upright 113 are connected at corresponding positions by the second upper cross member 122 and the second lower cross member 132, that is, the positions of the second upright 112 and the third upright 113, which are at the same height as the first upper cross member 121 and the first lower cross member 131, are connected by the second upper cross member 122 and the second lower cross member 132, respectively. The third upright 113 and the fourth upright 114 are connected at corresponding positions by a third upper beam 123 and a third lower beam 133, that is, the positions of the third upright 113 and the fourth upright 114, which are as high as the first upper beam 121 and the first lower beam 131, are connected by the third upper beam 123 and the third lower beam 133, respectively. The fourth vertical column 114 and the first vertical column 111 are connected at corresponding positions by a fourth upper cross beam 124 and a fourth lower cross beam 134, that is, the positions of the fourth vertical column 114 and the first vertical column 111, which are as high as the first upper cross beam 121 and the first lower cross beam 131, are connected by the fourth upper cross beam 124 and the fourth lower cross beam 134, respectively. Two first head sheave mounting positions 141 are provided between the upper portions of the first upright column 111 and the fourth upright column 114, a first head sheave 21 is provided at each first head sheave mounting position 141, two second head sheave mounting positions 142 are provided between the upper portions of the second upright column 112 and the third upright column 113, and a second head sheave 22 is provided at each second head sheave mounting position 142. The first friction wheel 41 and the second friction wheel 42 are respectively arranged on the ground at the left side and the right side of the derrick 1, the first steel wire rope 31 is wound on the first friction wheel 41, a part of the first steel wire rope 31 is wound on the first head sheave 21, the first skip 51 is connected to the first steel wire rope 31, the second steel wire rope 32 is wound on the second friction wheel 42, a part of the second steel wire rope 32 is wound on the second head sheave 22, and the second skip 52 is connected to the second steel wire rope 32. The first and

second friction wheels

41 and 42 are driven by first and second lift motors (not shown), respectively.

In the operation process of the coal mine vertical shaft hoisting system, the first hoisting motor drives the first friction wheel 41 to rotate, the first skip 51 is dragged to ascend and descend through the first steel wire rope 31, the second hoisting motor drives the second friction wheel 42 to rotate, and the second skip 52 is dragged to ascend and descend through the second steel wire rope 32. The coal mine vertical shaft lifting system comprises a rigid structure and a flexible structure, an obvious rigid-flexible coupling effect can occur between the rigid structure and the flexible structure of the coal mine vertical shaft lifting system in the operation process, the system load has the characteristics of time-varying property, strong coupling, nonlinearity and the like, the system belongs to a typical multi-source coupling vibration system, and the system has multi-order natural frequency. In the operation process of the coal mine vertical shaft lifting system, in order to ensure the operation safety and reliability, the lifting speed is usually limited within a certain range (such as 2-6m/s), and the coal mine vertical shaft lifting system has multi-stage natural frequency, so that the derrick is easy to resonate, and a large potential safety hazard exists.

Accordingly, there is a need in the art for a new solution to the above problems.

Disclosure of Invention

In order to solve the above problems in the prior art, that is, to solve the problem that the existing coal mine vertical shaft hoisting system is easy to resonate in the operation process and has a large potential safety hazard, the invention provides an anti-resonance derrick of the coal mine vertical shaft hoisting system, on one hand, the derrick comprises a first upright, a second upright, a third upright and a fourth upright, the first upright and the second upright are connected through a first upper cross beam and a first lower cross beam, the second upright and the third upright are connected through a second upper cross beam and a second lower cross beam at corresponding positions, the third upright and the fourth upright are connected through a third upper cross beam and a third lower cross beam at corresponding positions, and the fourth upright and the first upright are connected through a fourth upper cross beam and a fourth lower cross beam at corresponding positions; a first head sheave mounting position is arranged between the upper parts of the first upright post and the fourth upright post, and a second head sheave mounting position is arranged between the upper parts of the second upright post and the third upright post; a first inclined strut assembly is arranged between the first upright column and the second upright column and below the first lower cross beam, and/or a first inclined strut assembly is arranged between the third upright column and the fourth upright column and below the third lower cross beam.

In a preferred technical solution of the derrick, the first diagonal brace assembly includes two first diagonal braces, first ends of the two first diagonal braces are both connected to the first lower beam and/or the third lower beam, and second ends of the two first diagonal braces are respectively connected to the columns on both sides of the first lower beam and/or the third lower beam.

In a preferred technical scheme of the derrick, the two first inclined supporting rods are arranged in a splayed shape.

In a preferred technical solution of the above-mentioned derrick, a second bracing assembly is provided between the first column, the second column, the first upper beam and the first lower beam, and/or a second bracing assembly is provided between the third column, the fourth column, the third upper beam and the third lower beam.

In a preferred technical solution of the above derrick, the second diagonal brace assembly includes two second diagonal braces, first ends of the two second diagonal braces are both connected to the first upper beam and/or the third upper beam, and second ends of the two second diagonal braces are respectively connected to the columns on both sides of the first upper beam and/or the third upper beam.

In a preferred technical scheme of the derrick, the two second inclined supporting rods are arranged in a splayed shape.

In a preferred technical solution of the above derrick, the first diagonal brace includes at least two rod sections, and a buffer structure is disposed between adjacent rod sections.

In a preferred embodiment of the derrick, the first diagonal brace is provided with a counterweight structure.

In a preferred technical solution of the above derrick, the first diagonal brace is a hollow rod, and the counterweight structure is concrete filled in the hollow rod; or the counterweight structure is concrete coated outside the first diagonal brace.

In the technical scheme of the invention, the anti-resonance derrick comprises a first upright, a second upright, a third upright and a fourth upright, wherein the first upright and the second upright are connected through a first upper cross beam and a first lower cross beam; a first head sheave mounting position is arranged between the upper parts of the first upright post and the fourth upright post, and a second head sheave mounting position is arranged between the upper parts of the second upright post and the third upright post; a first inclined strut assembly is arranged between the first upright column and the second upright column and below the first lower cross beam, and/or a first inclined strut assembly is arranged between the third upright column and the fourth upright column and below the third lower cross beam. That is to say, set up the first bracing subassembly in the position that is located first bottom end rail below between the first stand of current derrick and second stand to and/or the position that is located third bottom end rail below between third stand and the fourth stand sets up the first bracing subassembly, through the setting of first bracing subassembly, has changed the natural frequency of derrick, makes the excitation frequency of current coal mine vertical shaft lift system in the operation keep away from the natural frequency of derrick, has reduced the risk that the derrick takes place resonance.

In another aspect, the invention provides a coal mine vertical shaft lifting system provided with an anti-resonance derrick as defined in any one of the preceding claims. It should be noted that the coal mine vertical shaft hoisting system has all the technical effects of the derrick, and the details are not repeated herein.

Drawings

Preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

fig. 1 is a schematic structural view of a conventional shaft hoist system;

fig. 2 is a schematic structural view of a derrick in a conventional vertical shaft hoisting system;

fig. 3 is a schematic structural view of a derrick of a vertical shaft hoisting system of a first embodiment of the invention;

fig. 4 is a schematic structural view of a derrick of a vertical shaft hoisting system of a second embodiment of the invention;

fig. 5 is a schematic structural view of a derrick of a vertical shaft lifting system according to a third embodiment of the present invention.

List of reference numerals:

1. a derrick; 111. a first upright post; 112. a second upright post; 113. a third column; 114. a fourth column; 121. a first upper cross member; 122. a second upper cross member; 123. a third upper cross member; 124. a fourth upper cross member; 131. a first lower cross member; 132. a second lower cross member; 133. a third lower cross member; 134. a fourth lower cross member; 141. a first antenna wheel mounting location; 142. a second head sheave mounting position; 15. a first diagonal brace; 16. a second diagonal brace; 21. a first head sheave; 22. a second head sheave; 31. a first wire rope; 32. a second wire rope; 41. a first friction wheel; 42. a second friction wheel; 51. a first skip; 52. a second skip; 6. a wellhead.

Detailed Description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.

It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; either directly or indirectly through intervening media, or through the communication between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. Furthermore, the terms "first," "second," "third," "fourth," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Based on the problems that a derrick is easy to resonate and has a large potential safety hazard in the operation process of the conventional coal mine vertical shaft lifting system mentioned in the background art, the inventor of the invention carries out deep analysis and research and provides a technical scheme for solving the problems. The inventor analyzes and researches the front 12-order matrix type of the derrick 1 when the coal mine vertical shaft lifting system shown in fig. 1 and fig. 2 operates in a conventional lifting speed range, and the research result specifically comprises the following steps: referring to fig. 2, the 1 st order vibration mode of the derrick 1 is wholly translated along the X axis, the 2 nd order vibration mode of the derrick 1 is wholly translated along the Z axis, the 3 rd order vibration mode of the derrick 1 is wholly swung around the Y axis, the 4 th order vibration mode of the derrick 1 is wholly swung around the Z axis, the 5 th order vibration mode of the derrick 1 is wholly translated along the Y axis, the 6 th order vibration mode of the derrick 1 is wholly swung around the X axis, the 7 th order vibration mode of the derrick 1 is reversely swung around the Y axis at the upper part and the lower part, the 8 th order vibration mode of the derrick 1 is reversely swung around the Z axis at the upper part and the lower part, the 9 th order vibration mode of the derrick 1 is swung around the X axis at the upper part, the 10 th order vibration mode of the derrick 1 is swung around the Z axis at the lower part, the 11 th order vibration mode of the derrick 1 is reversely swung around the Z axis at the lower part, and the 12 th order vibration mode of the derrick 1 is reversely swung around the Y axis and. The 7 th-12 th order vibration mode mainly takes vibration of a local vibration structure of the derrick as a main vibration mode, the amplitude is small, and the stability and the safety of the derrick can be ignored. The 1 st to 6 th order vibration modes mainly take the integral vibration of the derrick as the main vibration and have great influence on the stability and the safety of the derrick. When the coal vertical shaft lifting system operates at a conventional lifting speed, the excitation frequency is close to the fixed frequency corresponding to the 2 nd order vibration mode and the 3 rd order vibration mode of the derrick 1. The vibration generated by the derrick 1 is the resultant motion of the integral translation around the Z axis and the integral swinging around the Y axis, and the integral translation around the Z axis is taken as the main motion.

Based on the research results, the inventor provides an anti-resonance derrick of a coal mine vertical shaft lifting system, wherein the derrick comprises a first upright column, a second upright column, a third upright column and a fourth upright column, the first upright column and the second upright column are connected through a first upper cross beam and a first lower cross beam, the second upright column and the third upright column are connected through a second upper cross beam and a second lower cross beam at corresponding positions, the third upright column and the fourth upright column are connected through a third upper cross beam and a third lower cross beam at corresponding positions, and the fourth upright column and the first upright column are connected through a fourth upper cross beam and a fourth lower cross beam at corresponding positions; a first crown block mounting position is arranged between the upper parts of the first upright post and the fourth upright post, and a second crown block mounting position is arranged between the upper parts of the second upright post and the third upright post; a first inclined strut assembly is arranged between the first upright column and the second upright column and below the first lower cross beam, and/or a first inclined strut assembly is arranged between the third upright column and the fourth upright column and below the third lower cross beam.

The 2 nd order natural frequency and the 3 rd order natural frequency of the derrick 1 are greatly changed by arranging the first inclined strut assembly at a position below the first lower cross beam between the first upright column and the second upright column and/or arranging the first inclined strut assembly at a position below the third lower cross beam between the third upright column and the fourth upright column, so that the 2 nd order natural frequency and the 3 rd order natural frequency of the derrick 1 deviate from the excitation frequency. Meanwhile, a triangular supporting structure is formed between the upright columns and the cross beams, and the strength of the derrick 1 is enhanced. In the using process, the risk of resonance of the derrick 1 is reduced, the translation of the derrick 1 along the Z axis is weakened, and the stability and the safety of the derrick 1 are improved.

Referring to fig. 3, fig. 3 is a schematic structural view of a derrick of a vertical shaft lifting system according to a first embodiment of the present invention. As shown in fig. 3, the derrick 1 includes a first upright 111, a second upright 112, a third upright 113 and a fourth upright 114, and the first upright 111 and the second upright 112 are connected by a first upper cross member 121 and a first lower cross member 131. The second upright 112 and the third upright 113 are connected at corresponding positions by the second upper cross member 122 and the second lower cross member 132, that is, the positions of the second upright 112 and the third upright 113, which are at the same height as the first upper cross member 121 and the first lower cross member 131, are connected by the second upper cross member 122 and the second lower cross member 132, respectively. The third upright 113 and the fourth upright 114 are connected at corresponding positions by a third upper beam 123 and a third lower beam 133, that is, the positions of the third upright 113 and the fourth upright 114, which are as high as the first upper beam 121 and the first lower beam 131, are connected by the third upper beam 123 and the third lower beam 133, respectively. The fourth vertical column 114 and the first vertical column 111 are connected at corresponding positions by a fourth upper cross beam 124 and a fourth lower cross beam 134, that is, the positions of the fourth vertical column 114 and the first vertical column 111, which are as high as the first upper cross beam 121 and the first lower cross beam 131, are connected by the fourth upper cross beam 124 and the fourth lower cross beam 134, respectively.

Two first day wheel mounting positions 141 are arranged between the upper parts of the first upright column 111 and the fourth upright column 114, and two second day wheel mounting positions 142 are arranged between the upper parts of the second upright column 112 and the third upright column 113. A first diagonal bracing assembly is arranged between the first upright column 111 and the second upright column 112 and below the first lower cross beam 131, and a first diagonal bracing assembly is arranged between the third upright column 113 and the fourth upright column 114 and below the third lower cross beam 133, and comprises two first diagonal bracing 15. At a position between the first upright 111 and the second upright 112 and below the first lower cross beam 131, first ends of the two first diagonal support rods 15 are fixed to the first lower cross beam 131, and second ends of the two first diagonal support rods 15 are fixed to the first upright 111 and the second upright 112, respectively, so as to form a structure shaped like a Chinese character 'ba'. And at a position between the third upright post 113 and the fourth upright post 114 and below the third lower cross beam 133, first ends of the two first inclined supporting rods 15 are fixed to the third lower cross beam 133, and second ends of the two first inclined supporting rods 15 are fixed to the third upright post 113 and the fourth upright post 114 respectively, so that a splayed structure is formed.

The first inclined strut assembly comprises two first inclined struts 15, two ends of each first inclined strut 15 are respectively connected with the lower cross beam and the vertical column to form a triangular supporting structure, so that the supporting stability and strength are improved, meanwhile, the 2 nd order natural frequency and the 3 rd order natural frequency of the derrick 1 deviate relative to the excitation frequency, the risk of resonance of the derrick 1 is reduced, and the stability and the safety of the derrick 1 are improved.

It will be understood by those skilled in the art that the first diagonal brace assembly comprises two first diagonal braces 15, the first ends of the two first diagonal braces 15 are both fixed to the cross beam, and the second ends of the two first diagonal braces 15 are respectively fixed to the uprights at both sides of the cross beam to form the splayed structure, which is only a specific embodiment, and those skilled in the art can adjust the first diagonal brace assembly according to actual situations so as to use different applications, for example, the first diagonal brace assembly comprises two first diagonal braces, the two first diagonal braces are arranged in a crossed manner to form an X-shaped structure, or the first diagonal brace assembly comprises only one first diagonal brace, and both ends of the first diagonal brace are respectively connected to the connecting points of the uprights and the cross beam, etc. Further, the first diagonal brace assembly may be provided only at a position below the first lower beam 131 between the first column 111 and the second column 112, or may be provided only at a position below the third lower beam 133 between the third column 113 and the fourth column 114.

Referring to fig. 4, fig. 4 is a schematic structural view of a derrick of a vertical shaft lifting system according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that the first diagonal strut 15 comprises at least two segments, and a buffer structure, such as a rubber pad, a spring, etc., is disposed between adjacent segments. In the using process, the derrick 1 vibrates, the vertical columns and the cross beams deform slightly, two adjacent sections of the first inclined stay bar 15 vibrate slightly along the axial direction of the first inclined stay bar, the vibration energy of the two adjacent sections of the first inclined stay bar is absorbed by the buffer structure, the vibration of the first inclined stay bar 15 is weakened, and the vibration of the derrick 1 is further reduced.

Referring to fig. 5, fig. 5 is a schematic structural view of a derrick of a vertical shaft lifting system according to a third embodiment of the present invention. Preferably, the third embodiment is different from the first embodiment in that a second diagonal brace assembly is arranged between the first upright column 111, the second upright column 112, the first upper cross beam 121 and the first lower cross beam 131, and a second diagonal brace assembly is arranged between the third upright column 113, the fourth upright column 114, the third upper cross beam 123 and the third lower cross beam 133, and the second diagonal brace assembly includes two second diagonal braces 16.

Between the first upright 111, the second upright 112, the first upper beam 121 and the first lower beam 131, first ends of two second diagonal support rods 16 are fixed to the first upper beam 121, and second ends of two second support rods 16 are fixed to the first upright 111 and the second upright 112, respectively, so as to form a structure shaped like a Chinese character 'ba'. Between the third upright column 113, the fourth upright column 114, the third upper cross beam 123 and the third lower cross beam 133, first ends of two second diagonal braces 16 are fixed to the third upper cross beam 123, and second ends of two second diagonal braces 16 are fixed to the third upright column 113 and the fourth upright column 114 respectively, so that a structure in a shape like a Chinese character 'ba' is formed.

Through the arrangement, the strength between the first upright column 111 and the second upright column 112 and the strength between the third upright column 113 and the fourth upright column 114 are further improved, the stability and the strength of the derrick 1 are further improved, meanwhile, the 2 nd order natural frequency and the 3 rd order natural frequency of the derrick 1 are further deviated relative to the excitation frequency, the risk of the derrick 1 resonating is reduced, and the stability and the safety of the derrick 1 are improved.

It will be understood by those skilled in the art that the second diagonal brace assembly comprises two second diagonal braces 16, the first ends of the two second diagonal braces 16 are both fixed to the upper beam, and the second ends of the two second diagonal braces 16 are respectively fixed to the columns at both sides of the beam to form the "eight" shaped structure, which is just a specific embodiment, and those skilled in the art can adjust the second diagonal brace assembly according to the actual situation to use different applications, for example, the second diagonal brace assembly comprises two second diagonal braces, the two second diagonal braces are arranged in a cross manner to form the "X" shaped structure, or the two ends of the two second diagonal braces are respectively connected to the connecting points of the beam and the columns to form the "X" shaped structure, etc. Further, the second diagonal brace assembly may be provided only between the first column 111, the second column 112, the first upper beam 121, and the first lower beam 131, or may be provided only between the third column 113, the fourth column 114, the third upper beam 123, and the third lower beam 133.

Preferably, a counterweight structure is provided on the first diagonal strut 15. Specifically, the first diagonal brace 51 is a hollow bar, and the weight structure is concrete filled in the hollow bar. The weight of the first diagonal brace 51 is increased by filling the hollow rod with concrete, and the natural frequency of the derrick 1 is further changed, so that the 2 nd order natural frequency and the 3 rd order natural frequency of the derrick 1 are further deviated from the excitation frequency.

It will be understood by those skilled in the art that the first inclined supporting rod 51 is a hollow rod, and the counterweight structure is concrete filled in the hollow rod is just one specific embodiment, and those skilled in the art can adjust the first inclined supporting rod, for example, the counterweight structure can be concrete coated outside the first inclined supporting rod 51, or a counterweight block fixed on the first inclined supporting rod 51, such as an iron block, a stone block, etc.

In addition, the invention provides a coal mine vertical shaft lifting system which is provided with the anti-resonance derrick of any one of the above.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.

Claims

1. An anti-resonance derrick of a coal mine vertical shaft lifting system is characterized in that the derrick comprises a first upright, a second upright, a third upright and a fourth upright, the first upright and the second upright are connected through a first upper cross beam and a first lower cross beam, the second upright and the third upright are connected through a second upper cross beam and a second lower cross beam at corresponding positions, the third upright and the fourth upright are connected through a third upper cross beam and a third lower cross beam at corresponding positions, and the fourth upright and the first upright are connected through a fourth upper cross beam and a fourth lower cross beam at corresponding positions;

a first head sheave mounting position is arranged between the upper parts of the first upright post and the fourth upright post, and a second head sheave mounting position is arranged between the upper parts of the second upright post and the third upright post;

a first inclined strut assembly is arranged between the first upright post and the second upright post and below the first lower cross beam, and/or

And a first inclined strut assembly is arranged between the third upright column and the fourth upright column and below the third lower cross beam.

2. A derrick according to claim 1, characterised in that the first bracing assembly comprises two first bracing members, the first ends of which are both connected to the first and/or third lower beam, and the second ends of which are connected to uprights on either side of the first and/or third lower beam respectively.

3. A derrick according to claim 2, characterised in that the two first diagonal braces are arranged in a splay configuration.

4. A derrick according to claim 2, characterised in that a second bracing assembly is provided between the first upright, the second upright, the first upper beam and the first lower beam, and/or

And a second inclined strut assembly is arranged among the third upright column, the fourth upright column, the third upper cross beam and the third lower cross beam.

5. A derrick according to claim 4, characterised in that the second bracing assembly comprises two second bracing members, the first ends of which are both connected to the first and/or third head rail and the second ends of which are connected to uprights on either side of the first and/or third head rail respectively.

6. A derrick according to claim 5, characterised in that the two second diagonal braces are arranged in a splay configuration.

7. A derrick according to any of claims 2 to 6, characterised in that the first diagonal brace comprises at least two sections with a buffer structure provided between adjacent sections.

8. A derrick according to any of claims 2 to 6, characterised in that a counterweight structure is provided on the first diagonal brace.

9. A derrick according to claim 8, characterised in that the first diagonal brace is a hollow bar and the counterweight structure is concrete filled in the hollow bar; or

The counterweight structure is concrete coated outside the first diagonal brace.

10. A coal mine shaft hoist system, characterized in that it is provided with an anti-resonance mast as claimed in any one of claims 1 to 9.