JB/T 9174-1999 JB/T 9174-1999 Method for compiling process quotas for die forging material consumption JB/T9174-1999 Standard download decompression password: www.bzxz.net

JB/T9174---1999
This standard is a revision of JB/Z270-86 "Method for Compiling Material Consumption Process Quotas for Die Forgings". During the revision, the original standard was edited and the main technical content remained unchanged. This standard replaces JB/Z270-86 from the date of implementation. This standard is proposed and managed by the National Forging Standardization Technical Committee. The drafting unit of this standard: The Fourth Design Institute of the Ministry of Machinery Industry. The main drafter of this standard is Luo Qinglan.
1 Scope
Machinery Industry Standard of the People's Republic of China
Technological norm for die forgings material consumption
Compiting method of technological normfor die forgings material consumption This standard specifies the compilation method of technological norm for die forgings material consumption, JB/T 9174--1999
Replaces JB/Z270.-86
This standard is applicable to the compilation of technological norm for material consumption in factories (workshops) that mass-produce hot die forgings of steel. For die forging with steel ingots on hydraulic presses, it can be used as a reference.
2 Technical requirements
2.1 Definitions
This standard adopts the following definitions.
2.1.1 Technological loss
Material consumption necessary in the manufacturing process of die forgings according to technological regulations. 2.1.2 Non-process loss
Losses that may occur in the manufacturing process beyond the process loss regulations. 2.2 Requirements
2.2.1 Average length quota value of bars: Take the average value of the length specified in the national standard and calculate according to formula (1): Lmx±Lmi(1- n) +
Where: L-
Average length of bars, mm;
Maximum length of steel specified in national standards, mm;·Minimum length of steel specified in national standards, mm; L.---Permitted short length of steel specified in national standards, mm; n——Percentage of permitted short length of steel specified in national standards. Lmin + LoWww.bzxZ.net
If the enterprise has an agreement with the steel mill and supplies fixed length, the length shall be determined according to the agreement. 2.2.2 Material utilization rate, %
2.2.2.1 Part material utilization rate, calculated according to formula (2): K
× 100%
2.2.2.2 Product (or average part) material utilization rate, calculated according to formula (3): K.
Wu Zhong: ZG
The sum of the weights of all forgings used in a product; × 100%
The sum of the process quotas for material consumption of all forgings in the product. Approved by the State Machinery Industry Bureau on June 24, 1999 (1)
Implemented on January 1, 2000
2.2.2.3 Material utilization rate of forgings, calculated according to formula (4): 2.2.2.4 Utilization rate of forging of bad materials, calculated according to formula (5): 2.2.2.5 Utilization rate of material blanking, calculated according to formula (6): 2.2.2.6 Degree of refinement of forgings, calculated according to formula (7): 2.2.3 Determination of weight
JIB/T 9174- 1999
All weights are obtained by multiplying their volumes by the material density. Ga
×100%
X 100%
2.2.3.1 Part weight: According to the part drawing or provided by the ordering unit. 5
（6）
·（7)
2.2.3.2 Weight of forgings: The size is calculated based on the nominal size of the forging drawing plus 1/2 of the deviation (the inner surface size is calculated based on 1/2 of the deviation).
·When a forging is processed into several parts, the weight of the forging required for one part is calculated. For forgings with more complex shapes, the weight can be determined by weighing. 2.2.3.3 Weight of broken material: refers to the weight of the broken material. When a broken material can be made into several parts, it should be divided by the number of parts to obtain the weight of a single broken material.
2.2.3.4 Jaw weight of die forgings on die forging hammer: For forgings that require jaws, determine according to formula (8a) and formula (8b): Ik = (0.4～～0.8)D, (forgings <10 kg) Lk = (1.0～1.2)D, (forgings 10 kg) Where: Lk---jaw length, mm;
diameter of forging material, mm.
2.2.4 Weight of metal heating loss, calculated according to formula (9): g = G,o
Where: 3-heating burnout rate, %.
The first heating burnout rate is:
a) Coal-fired heating furnace: 2.5%~3.5%;
b) Oil-fired heating furnace: 2%~3%;
c) Gas-fired heating furnace: 1.5%~2.5%;
d) Resistance furnace: 1%~~1.5%;
e) Electric contact heating and induction heating: <0.5%. The subsequent burnout rate for each heating is calculated as 1/2 of the above value. 2.2.5 The loss in the cutting process is calculated according to formula (10) and formula (11): Ge = gt + gu + gy
L = n + t + (n + 1) + t
Wherein: L…--the length of the broken material, mm;
--the number of rings that can be cut from a bar;
--the length of each broken material, mm;
tl,l,…--the corresponding cutting loss length, mm. 332
. (8a)
(8h)
(10)
End loss of trimming
2.2.5.1 Allocation of end weight loss
JB/T9174—1999
Sawing or cutting consumption
Figure 1 Schematic diagram of process loss of bad material
Ends and material heads that cannot be used and are not used should be allocated to each forging. 2.2.5.2 End length of trimming
The maximum length of the trimming end cut on the shearing machine and press is as specified in Table 1. Table 1
End length of trimming
Bar diameter is greater than!
(or side length A) to
End length of trimming! ,
Cut off the trimmed end length on the sawing machine, calculated according to formula (12): 40
t. = 6 + (0.1 ~ 0.15)D + 5 Where: b—
Saw blade thickness, mm
The original bar material is directly forged and trimmed. The length of the end is calculated according to Wu (13): 1 =- 1/2
2.2.5.3 Not a multiple or the length of the pressure head loss The length of the bad material is less than the shortest clamping length, calculated according to formula (14): t, = Tmin +1/2
Where: tmir.
Not a multiple or the pressure head loss
0. 3D(0. 5A)
（13）
is the shortest clamping length of the clamping part of the shearing machine, press machine and sawing machine, mm (depending on the equipment type, specification and clamping head design).
The material return length is greater than the shortest tightening length, calculated according to formula (15): t, =1/2
2.2.5.4 Cutting loss length
Bar material cutting on the shearing machine, calculated according to formula (16): t = 1/2
Where: △/--~cutting length upper deviation, mm. Sawing machine 1: Cutting, calculated according to formula (17):
1, b + 41/2
Where: b
Saw blade thickness, mm;
M-cutting length upper deviation, mm.
The length of the deviation loss of the fixed length and multiple length materials is calculated according to formula (18): l., = 2△/3n
Where: △l--the deviation of the fixed length or multiple length materials, mm; n
-the number of forgings that can be made from a bar.
2.3 Material consumption process quota
(16)
2.3.1 Nature of material consumption process quota
JB/T 9174--1999
Material consumption process quota refers to the amount of material consumed to manufacture parts under certain production and technical conditions. It is composed of the weight of the product parts and various process losses in the manufacturing process. 2.3.1.1 Under the premise of ensuring product quality, combined with production conditions, the materials should be used in the most economical and reasonable way to make the quota advanced, reasonable and practical.
2.3.1.2 Material consumption process quotas shall be compiled according to parts and summarized according to product model, material category and specification. 2.3.1.3 Material consumption process quotas shall be modified in a timely manner as product part drawings and process changes are made to keep them consistent with the process documents. 2.3.1.4 Non-process losses shall not be included in the material consumption process quotas. 2.3.1.5 The quota should reflect the full and comprehensive utilization of materials, and try to make full use of the material heads, forging jaws, and the skin (or core) of the joint or the remanufactured scraps for other forgings.
2.3.1.6 When the jaws or skin (core) of part A are used as scraps for part B, part B is not calculated into the single-piece material consumption process quota, but the part weight and forging weight should be listed in the material consumption process quota details table for calculating the average material utilization rate of the product or workshop. The calculation method for set forgings is the same as above.
2.3.1.7 All kinds of cutting process losses and flat forging scraps should be allocated to each part. Among them, the usable material heads and flat forging scraps should be counted as new scraps and newly applied parts.
2.3.2 Composition of material consumption process quota (see Figure 2) 2.3.3 Basis for quota compilation
Material consumption process quota is compiled after process design, production preparation, production adjustment and trial production. The required basic data include:
a) parts drawing, parts list, parts weight and technical conditions; b) process route, forging drawing and forging T-process card; c) various standards, specifications, agreements and related data of materials d) special technical requirements for forging steel.
2.3.4 Calculation steps for material consumption process quota: a) Determine the part weight G:
b) Determine the forging weight G.;
c) Calculate the forging process loss weight G according to formula (19); G gr + gk + ge
d) Calculate the bad material weight Gr
G, = (Ga +G)/(1a)
e) Determine the bad material size D×l;
f) Calculate the cutting process loss weight GG=gt+ga+gy
g) Calculate the material consumption process quota G according to formula (21). G=G+G
h) calculate the material utilization rate K of the parts
2.3.5 Die forging material consumption process quota
The detailed list of die forging material consumption process quota is shown in Table 2.334
(19)
·(20)
(21)
JB/T9174-—1999
Lu Chongyi
JB/T 9174 --1999
gong!
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