This standard specifies the requirements and procedures for drawing networks. This standard applies to the drawing procedures for arrow-line and node-type network diagrams. JB/T 5056.2-1991 Network planning technology Network diagram drawing procedures JB/T5056.2-1991 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Network Planning Technology
Procedure for Drawing Network Diagrams
Subject Content and Scope of Application
This standard specifies the requirements and procedures for drawing network diagrams. This standard applies to the drawing of arrow-type and node-type network diagrams. 2 Reference Standards
JB/T5056.1 Network Planning Technology Terminology Graphic Symbols 3 Terms, Symbols, Codes
Terms, symbols, and codes shall be in accordance with JB/T5056.1. Requirements for Drawing Network Diagrams
JB/T5056.2—91
Drawing a network diagram generally consists of three parts: filling in a work list, a time calculation table, and drawing a network diagram. 4.1, Work List
4.1.1 Work List Format
The format of the work list shall be in accordance with Table 1.
Job number
How to fill in the job list
Job name
Serial number: Number the jobs in the order of their sequence. Job time
Job code
Previous job code
Job number: Number the jobs according to their position in the network. Arrow-type network diagrams are represented by two item numbers plus "", such as ①-②, ②-③, and node-type network diagrams are represented by Arabic numerals, such as 1, 2, 3. c.
Job name: Name the content of the job. Job time: Expressed by Arabic numerals plus dots, such as 4 and a half days, expressed as 4.5 days. Job code: The name of the job expressed in uppercase English letters or uppercase English letters plus Arabic numerals. Remarks: Explain the constraints on the job time or the requirements related to the job. f.
4.2 Time calculation table|| tt||4.2.1 Time calculation table format
The time calculation table format of the arrow network diagram is in accordance with Table 2. a.
Approved by the Ministry of Machinery and Electronics Industry on May 17, 1991 and implemented on July 1, 1992
Item number
Operation time"
Note: 1) Operation time refers to the time of the operation immediately preceding the item b.
JB/T5056.291
Earliest start time of the item
The time calculation table format of the node network diagram is in accordance with Table 3. Table 3
Operation time
4.2.2 Determination of time value
Earliest start time
4.2.2.1 There are two methods to determine the operation time. a.
Where; t
Empirical method. Determined according to actual experience.
Estimation method. Calculate according to formula (1):
Operation time:
- the most optimistic time;
the most conservative time;
- the most likely time.
4.2.2.2 Determination of event time
The most optimistic end time
a+4m+b
The earliest start time of the event is calculated according to formula (2): The latest end time of the event
The latest start time
tg()=max[te)+t,)]
(j-2,3,1,.)
In the formula: te0)
Earliest start time of the arrow event;
Earliest start time of the arrow event;
Operation time;
The maximum value of the sums in the brackets. The latest finishing time of the
item is calculated according to formula (3): t() = min[t() - ta,p)
1,n-2,n31)
wherein: t
The latest finishing time of the item at the tail of the arrow:
The latest finishing time of the item at the arrow head;
Operation time;
The minimum value of the differences in the brackets.
4.2.2.3 Determination of the start and end time of the operation
The earliest start time is calculated according to formula (4), ES=max[ESo+ta)]
Latest end time
Time difference of matter
Total time difference
·（4）
Where: ESa
Earliest start time:
Earliest start time of the immediate predecessor operation;
Operation time of the immediate predecessor operation;
The maximum value of the sums in the brackets.
The latest finish time is calculated according to formula (5): JB/T5056.2—91
LFg)=min(LF)-to))
Where: LF latest finish time;
-latest finish time of the next operation;
ta)—operation time of the next operation;
min—minimum value of the differences in brackets.
The earliest finish time is calculated according to formula (6): EFES+tg)
Where EF
Earliest finish time;
Earliest start time;
-operation time.
The latest start time is calculated according to formula (7): LS@) = LF() - tobZxz.net
Where: LSo-
Latest start time;
Latest finish time;
Operation time.
4.2.2.4 Time difference
In the formula: Sa>
The time difference of the event is calculated according to formula (8):
So=tt)
or S)=ttE()
Time difference of tail-of-arrow event:
Latest end time of the tail-of-arrow event;
Earliest start time of the tail-of-arrow event;
Time difference of arrow event;
Latest end time of arrow event;
Earliest start time of arrow event.
The total time difference is calculated according to formula (9):
TF@=LFOEFG)LSG-
Wherein: TF@
Total time difference:
LF<)—latest end time;
EF<—earliest end time:
（5）
·（8）
LS<)—latest start time;
ES)earliest start time.
4.2.3 Method for determining time value
JB/T5056.2—91
The earliest start time is calculated from the network starting event (starting operation), and is calculated from left to right in the order of event number (operation number), from small to large, until the termination event (termination operation). The latest end time is calculated from the network termination event (termination operation), from right to left in the reverse order of the event number (operation number), from large to small, until the start event (starting operation). 4.3 Drawing network diagram
Drawing principles
The arrow line is generally from left to right, and there should be no self-loop. The size and proportion of graphic symbols are uniform and appropriate, and the same symbol is the same size on a network diagram. The text description of the graphic is written from left to right. The event number and operation number should be expressed in Arabic numerals. Time should be expressed in Arabic numerals plus dots, such as 4 and a half days, expressed as 4.5 days. The arrow line should generally be parallel to the horizontal line.
The event number and operation number should be smaller on the left than on the right. Drawing requirements
4. 3. 2.1
Drawing requirements for arrow-type network diagrams
The arrow line of the network diagram without time coordinates should be long enough to fill in the relevant content. Try to avoid arrows crossing each other. If they must cross, they can be represented by "bridges". As shown in Figure 1, when arrows connect two items, the extension lines of the arrowhead and the tail of the arrow should pass through the center of the item symbol respectively. As shown in Figure 2. Figure
If there are multiple arrows between two items, except for one operation, the remaining operations should be separated by adding items. As shown in Figure 3. Figure 3
When an item issues more than two operations, it is recommended to follow Figure 4. When an item enters more than two operations at the same time, it is recommended to follow JB/T-5056.2-91
Figure 5. Network diagrams without time coordinates can be shown in Figures 6 and 7. Figure
f. Arrows should be distributed as evenly as possible.
4.3.2.2 Drawing requirements for node-type network diagrams The way arrows are issued is shown in Figure 8.
The way arrows enter is shown in Figure 9.
JB/T5056.2-91
There are five ways to connect the arrows between tasks, as shown in Figure 10. End to start
Start to start
End to end
5 Network diagram drawing procedure
Goal decomposition
JB/T5056.291
Start to finish
Start to start, finish to finish
Break down the overall goal of the project or plan into several tasks according to the work procedures. Fill in the task list
Determine the sequence and connection relationship between each task and the time of each task. c. Draw a network sketch
Draw a network sketch according to the task list.
Fill in the time calculation table
Calculate the time of each item according to the network sketch and number the task and item. Determine the critical path
Determine the critical path according to the items with zero time difference or the tasks with zero total time difference in the time calculation table. t.
Optimize the network
Repeatedly check, adjust and modify the network sketch in terms of the completion time of the construction period, the estimation of the task time and the rational use of resources, and finally achieve the target requirements.
Drawing of network diagram
See Appendix A (reference) for examples of drawing network diagrams. 13
Reinforcement network diagram
JB/T.5056.2—91
Appendix A
Example of drawing a network diagram
(reference)
The list of operations for the machining plan of Roots blower is shown in Table A1. Table A1
Operation No.
②一?
③一?
③一?
Operation Name
Rotor marking
Wall panel marking
Rotor planing surface
Casing marking||tt ||Plane planing
Rotor flush hole
Shell side processing
Wall panel boring
Rotor rough and fine planing
Main shaft processing
Other accessories processing
Gear processing
Shell drilling
Wall panel drilling
Shell assembly
Rotor balancing
Rotor grinding
Rotor group assembly
Blower assembly
Packaging and storage
The network diagram of Roots blower processing plan is shown in Figure A1. Operation time
(days)
Operation code
Previous operation code
K, O, Q, N
JB/T5056.2
JB/T5056.2-91
Roots blower processing plan time calculation table is shown in Table A2. Table A2
Time difference of items
Latest end time of items
Earliest start time of items
Operation time
(days)
Item number
JB/T5056.291
2-node network diagram
Roots blower processing plan operation list is shown in Table A3. Table A3
Previous operation code
Operation code
Operation time
Operation name
Operation number
Rotor marking
Wallboard marking
Rotor planing
Shell marking
Wallboard planing
Rotor flush mirror hole
Shell planing
Wallboard boring||t t||Rough and fine planing
Main shaft processing
Other parts processing
Gear processing
Bright body drilling
Root drilling
Shell assembly
Rotor balancing
Rotor grinding
Rotor assembly
English machine assembly
Packaging and storage
Roots blower processing plan network diagram is shown in Figure A2. b.
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