WO2021035893A1

WO2021035893A1 - Multi-level early warning method for overall efficiency of main shaft hoisting system

Info

Publication number: WO2021035893A1
Application number: PCT/CN2019/110987
Authority: WO
Inventors: 贾顺; 袁清和; 胡罗克
Original assignee: 山东科技大学
Priority date: 2019-08-23
Filing date: 2019-10-14
Publication date: 2021-03-04
Also published as: CN110555608A

Abstract

Provided is a multi-level early warning method for overall efficiency of a main shaft hoisting system. The method comprises: firstly, setting start-up rate, load rate and hoisting quality qualification rate control lower limit of a main shaft hoisting system, and thus performing calculation to acquire an overall efficiency control lower limit of the main shaft lifting system; then, acquiring the starting rate, the load rate, the hoisting quality qualification rate and the overall efficiency of the main shaft lifting system within an evaluation period; comparing and analyzing each acquired efficiency with a preset corresponding efficiency control lower limit, determining whether the system is in a normal state or not by combining the change trend of the efficiency; and if the system is in an abnormal state, determining the grade of abnormality, giving I-IV level early warning prompts, and displaying corresponding abnormal indexes on a display screen. An operator of the main shaft hoisting system can adjust and control the main shaft hoisting system in a targeted manner, and effective pre-event early warning of the overall efficiency of the main shaft hoisting system is achieved. The method is a practical and effective pre-event multi-level early warning method for the overall efficiency of the main shaft hoisting system.

Description

Multi-level early warning method for comprehensive efficiency of main shaft hoisting system

Technical field

The invention relates to the field of comprehensive efficiency early warning of the production system of a mining enterprise, in particular to a multi-level early warning method for the comprehensive efficiency of a main shaft raising system.

Background technique

The main shaft hoisting system of a mining enterprise is a key subsystem in the main coal flow transportation system. The comprehensive efficiency control of the main shaft hoisting system affects the overall output efficiency of the main coal flow system of the mining enterprise and the overall output efficiency of the enterprise. Therefore, studying the multi-level early warning method for the comprehensive efficiency of the main shaft improvement system of the mining enterprise is an important task for the overall efficiency control of the main coal flow system and the production system of the mining enterprise.

Research on the comprehensive efficiency management and control of the main shaft hoisting system of mining enterprises is rare. The patent document with the publication number CN108665168A discloses a method for evaluating and monitoring the comprehensive efficiency of the main well hoisting system for lean production, and gives the calculation formulas and calculation formulas of the operating rate, load rate, and quality improvement qualification rate that affect the overall efficiency of the main well hoisting system Obtain the method, and give a simple over-limit alarm to the overall efficiency of the main shaft hoisting system. The above-mentioned documents can realize the ex-post alarm when the overall efficiency of the main shaft hoisting system exceeds the control limit, but cannot realize the pre-warning of the overall efficiency of the main shaft hoisting system. Therefore, there is an urgent need to study the pre-warning methods for the main shaft to improve the overall efficiency of the system. In order to solve the above problems, the method of the present invention proposes a multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system, which realizes the operating rate and load rate that affect the overall efficiency of the main shaft hoisting system when the overall efficiency of the main shaft hoisting system does not exceed the limit. Or increase the quality qualification rate to exceed the limit, or the advance warning when the regularity is abnormal.

Summary of the invention

The purpose of the present invention is to provide a method capable of pre-warning the comprehensive efficiency of the main shaft hoisting system of a mining enterprise in advance, so as to realize the real-time effective management and control of the overall efficiency of the main shaft hoisting system.

A multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system includes the following steps:

Step 1. Set the lower limit of the comprehensive efficiency control of the main shaft hoisting system as

The lower limit of the operating rate control of the main shaft hoisting system is

The lower limit of the load rate control of the main shaft hoisting system is

And the lower limit of the main well hoisting system to improve the quality qualification rate control is

Step 2: Set the evaluation cycle time to Δt, and obtain the main shaft hoisting system _operating rate η operating, the load rate η _load and the improvement quality qualification rate η _{quality in the} evaluation cycle;

Step 3. Calculate the overall efficiency of the main shaft hoisting system based on the above-mentioned data of the main shaft hoisting system operating rate, load rate and hoisting quality qualification rate. The calculation model is:

η _overall ＝η _operating ×η _load ×η _quality

Among them: η _overall represents the overall efficiency of the main shaft hoisting system, η _operating means the operating rate of the main shaft hoisting system, η _load means the load rate of the main shaft hoisting system, and η _{quality the} pass rate of the main shaft hoisting system;

Step 4. Compare the overall efficiency of the main shaft hoisting system η _overall _{, the operating} rate of the main shaft hoisting system η operating, the load rate η _load and the improving quality qualification rate η _quality obtained during the evaluation period with the preset efficiency control lower limits;

Step 5. According to the above comparison results, analyze and judge the efficiency of the main shaft hoisting system: if the overall efficiency of the main shaft hoisting system satisfies the relational formula

The operating rate, the load rate and the improved quality qualification rate simultaneously satisfy the relationship:

with

It shows that the overall efficiency, operating rate, load rate and quality qualification rate of the main shaft hoisting system are not lower than the lower limit of control. At this time, it is still necessary to judge the trend of the overall efficiency of the main shaft hoisting system, operating rate, load rate, and improving quality qualification rate. , Any one of the efficiency indicators shows a continuous seven-point downward trend, indicating that the indicator has an abnormal trend, a level IV warning will be carried out, and the abnormal efficiency indicators will be displayed on the electronic screen; if the overall efficiency of the main well improves the system to meet the relationship

However, one of the indicators among the operating rate, the load rate, and the quality improvement qualification rate is less than or equal to the lower limit of control, that is, it satisfies the following formula:

or

It indicates that the main shaft hoisting system is abnormal, a level III warning is given, and the abnormal efficiency index is displayed on the electronic screen; if the overall efficiency of the main shaft hoisting system satisfies the relational formula

However, there are two indicators in the operating rate, load rate, and quality improvement pass rate that are less than or equal to the lower control limit, that is, meet

And

Or satisfied

And

Or satisfied

And

It indicates that the main shaft hoisting system is abnormal, a level II early warning is carried out, and the abnormal indicators are displayed on the electronic screen; if the overall efficiency of the main shaft hoisting system satisfies the relational formula

It indicates that the overall efficiency of the main shaft hoisting system exceeds the limit, and an I-level warning is issued, and the abnormal overall efficiency of the main shaft hoisting system and its abnormal sub-efficiency indicators (operating rate, load rate or improving quality qualification rate) will be displayed on the display screen; If there is no abnormality of the above four types, it indicates that the main shaft hoisting system is in a normal state, and the display on the electronic screen is normal;

Step 6. The operator of the main shaft hoisting system performs targeted adjustment and control of the main shaft hoisting system according to the warning level and the electronic screen display prompts in step 5, so that the efficiency of the main shaft hoisting system and the overall efficiency are controlled normally range.

In step 1, the lower limit of the operating rate of the main shaft hoisting system

Load rate control lower limit

Improve the lower limit of quality qualification rate

It is determined based on the statistical analysis of historical data of the main shaft hoisting system operating rate, load rate and hoisting quality qualification rate and combined with the experience of the main shaft hoisting system operator.

In step 1, the lower limit of the comprehensive efficiency control of the main shaft hoisting system

It is obtained by multiplying the lower limit of power-on rate control, the lower limit of load rate control, and the lower limit of elevating quality qualification rate. Therefore, the lower limit of the comprehensive efficiency control of the main shaft hoisting system is calculated as

In step 4, the specific method of comparing each efficiency index of the main shaft hoisting system with the corresponding lower limit of control is: the overall efficiency of the main shaft hoisting system η _overall and the lower limit of overall efficiency control

_{In contrast, the operating} rate of the main shaft hoisting system η operating and the operating rate control lower limit

In contrast, the load rate η _{load of the} main shaft hoisting system and the lower limit of the load rate control

In contrast, the main well hoisting system improves the quality qualification rate η _quality and the lower limit of the control of the quality qualification rate.

Compared.

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

The method of the present invention obtains the overall efficiency of the main well hoisting system through real-time acquisition of the operating rate, the load rate and the elevating quality qualification rate that affect the overall efficiency of the main well hoisting system, calculates the overall efficiency of the main well hoisting system, and compares the overall efficiency, operating rate, and load rate of the main well hoisting system Compare and analyze the lower limit of the quality qualification rate improvement, and analyze the overall efficiency of each main well hoisting system and the change trend of the operating rate, load rate and the improvement quality qualification rate, so as to realize the multi-level advancement of the overall efficiency of the main well improvement system. Early warning, to effectively control the overall efficiency of the main shaft hoisting system within the required range. The method of the present invention overcomes the shortcoming that the existing method only performs a post-event over-limit alarm on the overall efficiency of the main well hoisting system, and can realize pre-warning for the overall efficiency of the main well hoisting system. When the overall efficiency is not lower than the lower limit of control, the sub-indices are abnormal Or when the trend is abnormal, targeted multi-level early warning can be realized. The method of the invention is scientific and reasonable, and is a very practical and effective pre-warning method for the comprehensive efficiency of the main shaft hoisting system.

Description of the drawings

Figure 1 is a schematic flow diagram of the method of the present invention;

Figure 2 is a schematic diagram of the system configuration of the method of the present invention.

detailed description

The present invention will now be explained in detail in conjunction with embodiments and drawings.

The present invention provides a multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system. The flow diagram of the method of the present invention is shown in Fig. 1. First, obtain the main well hoisting system operating rate, load rate and hoisting quality qualification rate in the evaluation period, and then calculate the overall efficiency of the main well hoisting system in the evaluation period. Set the control lower limit of the main well hoisting system's operating rate, load rate, and improving quality qualification rate respectively, and calculate the comprehensive efficiency control lower limit of the main well hoisting system based on the operating rate, load rate and the lower limit of the qualified rate of improving quality. Compare the overall efficiency, operating rate, load rate, and lifting quality qualification rate of the main shaft hoisting system obtained during the evaluation period with their corresponding lower control limits, and analyze and judge the overall efficiency of the main shaft hoisting system in combination with the change trend of each efficiency. Whether it is in a normal state, and if it is in an abnormal state, determine the level of the abnormality, give a warning prompt of level I to IV, and display the corresponding abnormal indicators on the display screen. The main shaft hoisting system operator can adjust and control the main shaft hoisting system in a targeted manner, so as to realize the effective management and control of the overall efficiency of the main shaft hoisting system in advance.

Figure 2 is a schematic diagram of the system configuration of the method of the present invention. The main shaft hoisting system is equipped with a weight sensor. The weight sensor is used to obtain the actual lifting amount of the single hook of the main shaft hoisting system. The weight sensor is connected to the ZigBee wireless transmission system through the RS-485 interface. The ZigBee wireless transmission system passes RS-485/RS- The 232 interface is connected to the database server. The database server is installed with SQL Server or Oracle server, which is used to store the collected actual hoisting amount of the main shaft hoisting system. The database server communicates with the application server through the switch using the TCP/IP protocol. The application server is used to run the software programs required by the system, and is used to calculate and evaluate the operating rate, load rate, and quality of the main shaft hoisting system according to a certain time period. Qualification rate, calculation and analysis of the overall efficiency of the main shaft hoisting system. The display screen is used to display the early warning level of the main shaft hoisting system and the abnormal efficiency single value and comprehensive efficiency information.

The embodiment of the present invention is described by taking a main shaft hoisting system of a mining enterprise as an example, and the evaluation cycle time Δt is set to 3 hours. The method of the present invention is used to perform multi-level early warning of the overall efficiency of the main shaft hoisting system, and the early warning information is displayed on the display screen.

1. Set the overall efficiency, operating rate, load rate of the main well hoisting system and the lower limit of the qualification rate of the hoisting quality

In the present invention, the control lower limit of the main shaft hoisting system operating rate, load rate, and lifting quality qualification rate is based on the statistical analysis of historical data of the main shaft hoisting system operating rate, load rate, and lifting quality qualification rate, and combined with the main shaft hoisting system operator. Determined by experience. In this embodiment, the lower limit of the operating rate of the main shaft hoisting system is

90.0%, the lower limit of the load rate control of the main shaft hoisting system

95.0%, the lower limit of the main well hoisting system's elevating quality qualification rate

Is 90.0%. The lower limit of the comprehensive efficiency control of the main shaft hoisting system is determined by the formula

Calculated. Therefore, the lower limit of the comprehensive efficiency control of the main shaft hoisting system in this embodiment is

2. Obtain the operating rate, load rate and quality qualification rate of the main shaft hoisting system

Because the evaluation cycle time Δt=3 hours, the main shaft hoisting system operating rate, load rate and hoisting quality qualification rate are obtained every 3 hours. The mining enterprise has carried out lean management for a period of time, and periodically records the data on the operating rate, load rate, and elevating quality qualification rate of the main shaft hoisting system. Taking 8:00-11:00 on a working day as an example, it is obtained that the operating rate of the main shaft hoisting system of the mine is 90.3%, the load rate is 96.1%, and the qualification rate of the hoisting quality is 90.5%.

3. Obtain the overall efficiency of the main well to improve the system

Based on the above-mentioned main shaft hoisting system operating rate, load rate and hoisting quality qualification rate data, the overall efficiency of the main shaft hoisting system is calculated, and the calculation model is η _overall = η _operating × η _load × η _quality . Among them, η _overall represents the overall efficiency of the main shaft hoisting system, η _operating means the operating rate of the main shaft hoisting system, η _load means the load rate of the main shaft hoisting system, and η _{quality the} pass rate of the main shaft hoisting system. Following the previous example, still taking 8:00-11:00 on a working day as an example, we have obtained the mine’s main shaft hoisting system _operating rate η operating = 90.3%, load rate η _load = 96.1%, and the improvement quality qualification rate η _quality ＝ 90.5%. _{Putting the} above data into the formula η overall = η _operating × η _load × η _quality , it can be calculated that the overall efficiency of the main well improvement system η _overall = 78.5% in the evaluation period.

4. Comparison of the overall efficiency of the main shaft hoisting system and its sub-efficiencies

The overall efficiency of the main shaft hoisting system and its sub-efficiencies (operating rate, load rate, and hoisting quality qualification rate) obtained are compared and analyzed with the lower control limit of the corresponding index. In this embodiment, the lower control limits of the overall efficiency, operating rate, load rate, and elevating quality qualification rate of the main shaft hoisting system are respectively

with

Still taking a certain working day from 8:00-11:00 on a certain working day as an example, the overall efficiency of the main shaft hoisting system in the evaluation period is η _overall ＝78.5%, the _operating rate η operating ＝90.3%, and the load rate It is η _load = 96.1%, and the quality improvement qualification rate is η _quality = 90.5%. Then the main well will improve the _overall system efficiency η overall = 78.5% and the overall efficiency control lower limit

_{In contrast, the operating} rate of the main shaft hoisting system η operating = 90.3% and the operating rate control lower limit

In contrast, the load rate of the main shaft hoisting system η _load = 96.1% and the lower limit of the load rate control

In contrast, the main well hoisting system improves the quality qualification rate η _quality ＝90.5% and the lower limit of the improvement quality qualification rate control

Compared.

5. According to the comparison result, analyze and judge whether there is an abnormality in the main shaft hoisting system and give an early warning

Still taking a certain working day from 8:00 to 11:00 on a certain working day as an example, the overall efficiency of the main shaft improvement system and its sub-efficiencies (operating rate, load rate, and improvement quality qualification rate) and corresponding The lower control limit of the index is compared with the results, and the relationship is satisfied

And the operating rate, the load rate and the improved quality qualification rate simultaneously satisfy the relationship:

with

It shows that the overall efficiency, operating rate, load rate and quality qualification rate of the main shaft hoisting system are not lower than the lower limit of control. At this time, it is still necessary to judge the trend of the overall efficiency of the main shaft hoisting system, operating rate, load rate, and improving quality qualification rate. It is judged that the seven consecutive load rate data obtained are respectively η _load,1 = 97.1%, η _{load, 2} = 96.9%, η _{load, 3} = 96.7%, η _{load, 4} = 96.6%, η _{load, 5} = 96.3%, η _load,6 = 96.1%, and η _{load, 7} = 96.0%, then the following relationship is satisfied: η _{load, 1} > η _{load, 2} > η _{load, 3} > η _{load, 4} > η _{load, 5} > η _load,6 >η _load,7 , indicating that the load rate has a continuous downward trend, an IV level warning will be carried out, and seven consecutive load rates with abnormalities (η _load,1 = 97.1%, η _{load, 2} = 96.9%) , Η _load,3 = 96.7%, η _{load, 4} = 96.6%, η _{load, 5} = 96.3%, η _{load, 6} = 96.1% and η _{load, 7} = 96.0%) index values are displayed on the electronic screen.

Taking the 14:00-17:00 of the working day as an example, the _operating rate of the main shaft hoisting system η operating = 89.7%, the load rate η _load = 96.0%, and the improvement quality qualification rate η _quality = 92.8% are obtained. _{Putting the} above data into the formula η overall = η _operating × η _load × η _quality , it can be calculated that the overall efficiency of the main shaft improvement system η _overall = 79.9% in the evaluation period. And the lower limit of the comprehensive efficiency control of the main shaft hoisting system

Boot rate control lower limit

Load rate control lower limit

And improve the lower limit of quality qualification rate control

Comparative analysis found that the relationship is satisfied

At the same time the operating rate satisfies the relationship

The load rate and the qualified rate of improving the quality are both greater than the lower control limit of the corresponding index, and a Level III warning will be carried out, and there will be an abnormal start-up rate

The index value is displayed on the electronic screen.

Taking the 17:00-20:00 of this working day as an example, the _operating rate of the main shaft hoisting system η operating = 89.5%, the load rate η _load = 94.8%, and the improvement quality qualification rate η _quality = 92.8% are obtained. _{Putting the} above data into the formula η overall = η _operating × η _load × η _quality , it can be calculated that the overall efficiency of the main shaft improvement system η _overall = 78.7% in the evaluation period. And the lower limit of the comprehensive efficiency control of the main shaft hoisting system

Boot rate control lower limit

Load rate control lower limit

And improve the lower limit of quality qualification rate control

Comparative analysis found that the relationship is satisfied

At the same time, the operating rate and the load rate satisfy the relationship

with

Improve the quality qualification rate to be greater than the lower control limit of the corresponding index, carry out a level II early warning, and will have an abnormal operating rate

And load rate

The index value is displayed on the electronic screen.

Taking the 20:00-23:00 of this working day as an example, the _operating rate of the main shaft hoisting system η operating = 89.7%, the load rate η _load = 94.3%, and the improvement quality qualification rate η _quality = 90.2% are obtained. _{Putting the} above data into the formula η overall = η _operating × η _load × η _quality , it can be calculated that the overall efficiency of the main well improvement system η _overall = 76.3% in the evaluation period. And the lower limit of the comprehensive efficiency control of the main shaft hoisting system

Boot rate control lower limit

Load rate control lower limit

And improve the lower limit of quality qualification rate control

Comparative analysis found that the relationship is satisfied

It indicates that the comprehensive efficiency of the main shaft hoisting system exceeds the limit, and if a Class I warning is carried out, there will be abnormal overall efficiency of the main shaft hoisting system.

And its anomalous sub-indicators (availability rate

Load factor

) Is displayed on the display.

6. According to the warning reminder, the main shaft hoisting system is controlled in a targeted manner so that each efficiency single value and comprehensive efficiency are controlled within the normal range

The method of the present invention can be used in advance multi-level early warning of the overall efficiency of the main shaft hoisting system of a mining enterprise to realize effective management and control of the overall efficiency of the main shaft hoisting system. When the overall efficiency of the main shaft hoisting system does not exceed the limit, but the trend is abnormal, it can also be used Carry out multi-level early warning prompts in advance to ensure the high-efficiency operation of the main shaft hoisting system.

Finally, it should be noted that the above implementation cases are only used to illustrate the technical solutions of the present invention and not to limit them. Modifications or equivalent replacements to the technical solutions of the present invention do not depart from the purpose and scope of the method of the present invention, which should be covered by the present invention Within the scope of the claims.

Claims

A multi-level early warning method for the comprehensive efficiency of a main shaft hoisting system is characterized in that it comprises the following steps:

Step 1. Set the lower limit of the comprehensive efficiency control of the main shaft hoisting system as
The lower limit of the operating rate control of the main shaft hoisting system is
The lower limit of the load rate control of the main shaft hoisting system is
And the lower limit of the main well hoisting system to improve the quality qualification rate control is

Step 2: Set the evaluation cycle time to Δt, and obtain the main shaft hoisting system operating rate η operating, the load rate η load and the improvement quality qualification rate η quality in the evaluation cycle;

Step 3. Calculate the overall efficiency of the main shaft hoisting system based on the above-mentioned data of the main shaft hoisting system operating rate, load rate and hoisting quality qualification rate. The calculation model is:

η overall ＝η operating ×η load ×η quality

Among them: η overall represents the overall efficiency of the main shaft hoisting system, η operating means the operating rate of the main shaft hoisting system, η load means the load rate of the main shaft hoisting system, and η quality the pass rate of the main shaft hoisting system;

Step 4. Compare the overall efficiency of the main shaft hoisting system η overall , the operating rate of the main shaft hoisting system η operating, the load rate η load and the improving quality qualification rate η quality obtained during the evaluation period with the preset efficiency control lower limits;

Step 5. According to the above comparison results, analyze and judge the efficiency of the main shaft hoisting system: if the overall efficiency of the main shaft hoisting system satisfies the relational formula
The operating rate, the load rate and the improved quality qualification rate simultaneously satisfy the relationship:
with
It shows that the overall efficiency, operating rate, load rate and quality qualification rate of the main shaft hoisting system are not lower than the lower limit of control. At this time, it is still necessary to judge the trend of the overall efficiency of the main shaft hoisting system, operating rate, load rate, and improving quality qualification rate. , Any one of the efficiency indicators shows a continuous seven-point downward trend, indicating that the indicator has an abnormal trend, a level IV warning will be carried out, and the abnormal efficiency indicators will be displayed on the electronic screen; if the overall efficiency of the main well improves the system to meet the relationship
However, one of the indicators among the operating rate, the load rate, and the quality improvement qualification rate is less than or equal to the lower limit of control, that is, the following relationship is satisfied:
or
or
It indicates that the main shaft hoisting system is abnormal, a level III warning is given, and the abnormal efficiency index is displayed on the electronic screen; if the overall efficiency of the main shaft hoisting system satisfies the relational formula
However, there are two indicators in the operating rate, load rate, and quality improvement pass rate that are less than or equal to the lower control limit, that is, meet
And
Or satisfied
And
Or satisfied
And
It indicates that the main shaft hoisting system is abnormal, a level II early warning is carried out, and the abnormal indicators are displayed on the electronic screen; if the overall efficiency of the main shaft hoisting system satisfies the relational formula
It indicates that the overall efficiency of the main shaft hoisting system exceeds the limit, and an I-level warning is issued, and the abnormal overall efficiency of the main shaft hoisting system and its abnormal sub-efficiency indicators (operating rate, load rate or improving quality qualification rate) will be displayed on the display screen; If there is no abnormality of the above four types, it indicates that the main shaft hoisting system is in a normal state, and the display on the electronic screen is normal;

Step 6. The operator of the main shaft hoisting system performs targeted adjustment and control of the main shaft hoisting system according to the warning level and the electronic screen display prompts in step 5, so that the efficiency of the main shaft hoisting system and the overall efficiency are controlled normally range.
The multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system according to claim 1, wherein in step 1, the lower limit of the operating rate of the main shaft hoisting system is controlled
Load rate control lower limit
Improve the lower limit of quality qualification rate
It is determined based on the statistical analysis of historical data of the main shaft hoisting system operating rate, load rate and hoisting quality qualification rate and combined with the experience of the main shaft hoisting system operator.
The multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system according to claim 1, wherein, in step 1, the lower limit of the comprehensive efficiency control of the main shaft hoisting system is
It is obtained by multiplying the lower limit of power-on rate control, the lower limit of load rate control, and the lower limit of elevating quality qualification rate. Therefore, the lower limit of the comprehensive efficiency control of the main shaft hoisting system is calculated as
The multi-level early warning method for the comprehensive efficiency of the main shaft hoisting system according to claim 1, wherein, in step 4, the specific method of comparing each efficiency index of the main shaft hoisting system with the corresponding lower control limit is: the comprehensive efficiency of the main shaft hoisting system η overall and overall efficiency control lower limit
In contrast, the operating rate of the main shaft hoisting system η operating and the operating rate control lower limit
In contrast, the load rate η load of the main shaft hoisting system and the lower limit of the load rate control
In contrast, the main well hoisting system improves the quality qualification rate η quality and the lower limit of the control of the quality qualification rate.
Compared.