Some standard content:
Machinery Industry Standards of the People's Republic of China
Technical Conditions for Iron Castings for Fans
Subject Content and Scope of Application
This standard specifies the technical requirements, test methods and acceptance rules for iron castings for fans. JB/T 6887-93
This standard applies to gray cast iron, ductile iron and medium manganese anti-wear ductile iron used in centrifugal and axial flow fans, blowers, compressors and Roots and Yeh blowers. Castings of high-silicon corrosion-resistant cast iron, heat-resistant cast iron and other alloy cast irons (hereinafter referred to as castings). 2 Reference standards
GB223
GB228
GB229
GB230
GB231
GB1348
GB 3180||tt| |GB5977
Methods for chemical analysis of steel and alloys
Metal tensile test method
Metal Charpy (U-notch) impact test method Metal Rockwell hardness test method
Metal Brinell hardness test method
Nodular cast iron parts
Technical conditions for medium manganese anti-wear ductile iron parts
Gray cast iron mechanical property test method
GB 6060.1||tt| |GB6414
GB7216
GB8491
GB9437
GB9439
GB9441
Surface roughness comparison sample
Casting surface
Dimensional tolerance of castings
Grey cast iron metallography
High silicon corrosion-resistant iron castingsbzxZ.net
Heat-resistant cast iron parts
Gray iron castings
Metallographic inspection of ductile iron
GB/T 11350
JB/Z 179
JB/Z85
Machining allowance for castings
Medium manganese anti-wear Metallographic diagram of ductile iron
Wood mold grade and technical conditions for casting
JB/T 6886
JB/T 6889
3 Technical requirements
Ventilation Technical conditions for machine coating
Technical conditions for defect repair of cast iron parts for fans 3.1 Various types of cast iron parts in this standard should use grades that comply with the regulations of GB9439, GB1348, GB9437, GB8491, and GB3180. 3.2 Production methods and heat treatment
Castings should be annealed to eliminate internal stress. The production method and heat treatment of castings are determined by the supplier, but they must meet the grades and relevant technical properties specified in this standard.
If the purchaser has special requirements for the heat treatment method, it shall be agreed upon by both parties. 3.3 Mechanical properties and chemical composition
The Ministry of Machinery Industry of the People's Republic of China approved on 1993-07-13 for implementation on 1994-07-01
217
JB/T688793
3.3. 1 The acceptance basis for gray iron castings is based on tensile strength; the acceptance basis for ductile iron castings is based on tensile strength and elongation; the acceptance basis for medium manganese wear-resistant ductile iron castings is based on impact value and hardness; the acceptance basis for corrosion-resistant castings is based on chemical composition, resistance The acceptance of hot iron castings is based on chemical composition and room temperature tensile strength. If there are other special requirements, they should be noted in the order agreement. 3.3.2 The tensile strength and bending strength of castings, among which gray iron castings, high-silicon corrosion-resistant iron castings, and RT-type heat-resistant iron castings, should be based on $30+mm single-cast test rods cast in a sand mold; ductile iron castings , RQT type heat-resistant iron castings, the value of the Y-shaped single casting test block of 25mm×55mm should be used as the basis for acceptance. The impact value of medium manganese ductile iron castings should be based on the value of a 20mm×20mm×110mm single impact test block as the basis for acceptance. For castings with special requirements, when casting test rods and test blocks need to be attached, this should be noted in the drawing or order agreement. And the measured mechanical properties and chemical composition values ??should comply with the provisions of Article 3.1. 3.3.3 The hardness of the machined surface of fan castings should generally be controlled below HB255; no hardness inspection will be performed on the non-machined surface. For castings with high hardness that affects processing performance, high-temperature annealing heat treatment is allowed. 3.4 Metallographic structure
The metallographic structure inspection results of castings are only used as a reference for quality control. If the buyer has requirements for metallography, gray iron castings shall comply with GB7216, ductile iron castings shall comply with GB9441, the spheroidization level shall not be lower than level 4, medium manganese wear-resistant ductile iron castings shall comply with JB/Z179, heat-resistant parts and corrosion-resistant parts Please refer to GB7216 and GB9441 for details: The supply and demand parties shall agree on specific regulations such as the level of inspection items and sampling locations and quantities. 3.5 Geometric shape, machining allowance and dimensional tolerance 3.5.1 The geometric shape and size of the casting should comply with the drawing or ordering appearance and relevant agreements. Wooden molds should be executed according to the second level precision of JB/Z85. The draft angle of castings shall comply with the provisions of Appendix A. 3.5.2 The machining allowance of castings is as shown in the drawing, and if there are no special requirements in the ordering agreement, the H-level regulations corresponding to dimensional tolerances in GB/T11350 shall be followed (see Appendix B).
3.5.3 If there are no general dimensional tolerances specially noted in the drawings, they shall be implemented according to the CT13 level of GB6414. See Appendix C for the tolerance values. Generally, the tolerance zones should be distributed symmetrically, that is, half of the tolerance takes positive values ??and the other half takes negative values. For some special cases, with the agreement between the design and casting production parties, the tolerance can be partially or completely positive or negative. 3.5.4 Dimensional tolerances of special parts of fan castings 3.5.4.1 Dimensional tolerances of casting wall thickness, rib thickness, web plate thickness and return chamber and diffuser blade thickness, when the basic size is less than 20mm, shall be implemented according to CT12 level of GB6414; When the basic size is equal to or greater than 20mm, it shall be implemented according to CT14 level of GB6414. 3.5.4.2 The thickness and dimensional tolerances of faceted flanges and fluid inlet and outlet flanges in castings such as casings, bearing bodies, gearboxes, oil pumps, and casings shall be implemented in accordance with the CT14 level of GB6414,
3.5 .4.3 Due to the eccentricity of the misaligned box, coaxiality deviations occur in rotating castings such as pulleys and shaft disks. Under the condition of ensuring sufficient machining volume on the outside of the shaft hole and the rim, the inner side of the rim and other non-machined surfaces must be aligned with the axis of the shaft hole. The coaxiality tolerance should comply with the provisions of Table 1 (see Figure 1). Table 1 Coaxiality tolerance of rotating castings
Maximum outer gallery diameter
Tolerance value ±
300
3
>300～500| |tt||4
>500~800
5
>800
6
mm
3.5.4.4 chassis ( See Figure 2) The opening of the scroll chamber (side A) should ensure that there is sufficient machining allowance, and no black skin is allowed to be left. The position and size of the umbilical ring for installing the seal, bushing, and partition should be adjusted when processing and marking. Taking the midline of the cochlear chamber as the benchmark, after processing, it must be ensured that the thickness E of the upper teeth of the umbilical ring is not less than 80% of the original size. In order to prevent the umbilical ring C from being displaced excessively, the offset of the axis of the cochlear chamber in the axial direction shall not be greater than 3 mm. The radial offset of the axis of the casing, bearing seat, cover, gearbox and other parts should not be greater than 3mm to avoid excessive staggered steps. 218
?
?
JB/T6887-93
A
Figure 1
Figure 2
@| |tt||3.5.4.5 The tolerance of the size of the flow channel in the casing volute (Figure 2) H and B, when the size is less than or equal to 120mm, should not be greater than 4% of the basic size of the measured part; when the flow When the track size is greater than 120mm, it should not be greater than the basic size ±2%. 3.5.4.6 The dimensional tolerances within the reflow chamber, partitions and diffuser flow channels should be within ±8% of the basic dimensions of the measured parts, and the maximum should not exceed ±5mm.
3.5.4.7 The position tolerance of the bosses (umbilicus) on the casing, bearing seat, gearbox, shell, base and other castings shall not be greater than 4mm, otherwise it needs to be corrected.
3.5.4.8 Dimensional tolerances such as overall height dimension A, inner cavity depth I, bottom surface machining tool B, and boss height center for jointing of bearing side covers of three-out-of-box castings (Figure 3) such as bearing seats and gearboxes. , should comply with the requirements of Table 2. 219
3.6
Maximum verandah size
700
≥700
Weight
A
3||tt ||5
JB/T6887--93
Figure 3
Dimensional tolerance of three unboxing castings
Table 2
Part
H
4
6
bits
B
6
8
C
4| |tt||5
mm
Casting weight If there are no special requirements in the order agreement, the weight deviation of castings produced with the same drawing or model should not be greater than 7%. 3.7 Surface quality
3.7.1 The surface roughness of the flow channel of castings such as casings, partitions, diffusers, etc., more than 70% of the surface shall comply with (R.50 of GB6060.1, and the rest shall comply with R.100; the surface roughness of other general castings shall not exceed R100. If there are special requirements, they should be indicated in the order contract.
3.7.2 Unless otherwise specified, castings are delivered in an unprocessed state. However, they should be cleaned, trimmed, and the core bone, sticky sand, cavity residues and pouring and riser residues should be removed (residues are allowed on the processed surface, but not more than 6mm). Bearing The sand stuck on the parts of the castings that contact the fluid, such as the seat, the inner cavity of the gearbox, the casing, and the reflux chamber, must be carefully cleaned. 3.7.3 The straightness deviation of the exposed non-machined surface of the casting shall not exceed 3mm over any 600mm length in the same casting plane. 3.7.4 Non-machined surface misalignment value
3.7.4.7
The misalignment value of the non-machined surface (external surface) of the casting shall comply with the provisions of Table 3. Table 3 Misalignment value
Maximum size of casting
250
250
630
1600
4 000
6300
630
1600
4000
6300
Non-machined surface misalignment value
1.0
2.)
3.0
4. (
5.0
6. 0
After misalignment occurs on the exposed non-machined surface of the casting, it should be scraped into a 10° slope shape (as shown in Figure 4). 3.7.4.2
Misalignment
220
Figure 4
Scraped away part
110
mm
3.8 Finishing
JB/T 6887.-93
For the staggered steps at the joints of the upper and lower parts of the casing, the gearbox seat and the cover, etc., when not exceeding 1/5 of the wall thickness, the staggered steps should be chamfered 60° after machining.
3.9 Defects
3.9.1 Cracks, cold shuts, shrinkage and other defects that affect the use of castings are not allowed. 3.9.2 Surface defects within the machining allowance are allowed on the machined surface of the casting. 3.9.3 The types, ranges, quantities and defects of defects allowed on the non-machined surface and inside of the casting Repair regulations shall be implemented in accordance with the provisions of JB/T6889.
3.10 Leakage test
All castings that need to undergo oil seepage, pressure bearing and other leakage tests shall be indicated on the drawings or order agreements and shall comply with the following regulations: 3.10.1 Transmissions, bearing boxes, oil tanks that store thin oil, and housings, pumps, shells, valve bodies, etc. with working pressures less than or equal to 0.25MPa shall be subjected to leakage tests before primer painting. After cleaning the inside and outside of the wall, immerse in oil or apply kerosene. No leakage is allowed within a duration of 15 minutes.
3.10.2 The flow channel of the water-cooled bearing that bears pressure and various housings, pump housings, valve bodies, etc. with working pressures greater than 0.25MPa (gauge pressure) shall be subjected to water pressure tests. The test pressure shall be 1.5 times its working pressure, and there shall be no leakage within 30 minutes of pressure maintenance. 3.10.3 For blowers and compressor casings used for toxic or flammable gases, an inert gas should be used to pressurize to the rated pressure (1.5 times the working pressure of the casing), maintain the pressure for 30 minutes, and use a foaming liquid to check for gas leakage. 3.11 Primer
After finishing, heat treatment and qualified inspection, the casting should be cleaned according to the relevant provisions of JB/T6886 "Technical Conditions for Coating of Fans" to achieve no rust, no paint deposits, etc. Within 24 hours after surface cleaning, the non-machined surface should be painted with iron red anti-rust primer. If there are special requirements for primer, it should be indicated on the drawing or order agreement. 4 Test methods and inspection rules
4.1 The casting shall be inspected and accepted by the technical inspection department of the production unit in accordance with the technical requirements of Chapter 3, and the purchaser has the right to inspect the casting. 4.2 The method of selecting the sample shall be implemented in accordance with Article 3.3.2. If the casting needs heat treatment. The specimens and castings are heat treated in the same furnace. When only internal stress is eliminated, the specimens do not need to be heat treated. 4.3 Test methods for mechanical properties of castings. The tensile test of gray cast iron parts and RT type heat-resistant castings, and the bending test of high silicon corrosion-resistant parts are carried out in accordance with GB5977; the tensile test of ductile iron parts and heat-resistant ductile iron (RQT) parts is carried out in accordance with GB228. The impact test of medium manganese ductile iron parts is carried out in accordance with GB229, and its Rockwell hardness test is carried out in accordance with GB230; the Brinell hardness test of other various cast irons is carried out in accordance with GB231. When measuring the hardness directly on the surface of the casting, the thickness of the casting surface should be removed by not less than 2mm and carefully leveled. The measurement position should be selected on the working surface not less than 10mm away from the edge of the casting. The chemical analysis method of castings is carried out in accordance with the relevant provisions of GB223. 4.4 Division of batches
4.4.1 Castings cast from the same package of molten iron are one batch. 4.4.2 The maximum weight of each batch is a 2000kg casting that is clean and intact. If the weight of a casting is greater than 2000kg, it will be a separate batch.
4.4.3 When a large amount of molten iron of the same grade is melted continuously, the maximum weight of each batch shall not exceed the weight of the castings poured within 2 hours. If the melting volume of a brand of molten iron is large, and under the production conditions of fixed raw materials and stable melting process, several batches can be combined into one group for acceptance after consultation and agreement between the supply and demand parties. 4.5 The material acceptance of castings shall be carried out in accordance with the provisions of Article 3.3. At least one group (three) of specimens shall be taken from each batch for relevant mechanical property tests and chemical composition analysis. During the inspection, one specimen shall be tested first. If it meets the requirements, the batch of castings is qualified in terms of material; if the test results do not meet the requirements, it is allowed to take two more specimens from the same batch for re-inspection. If both meet the requirements, the material of the batch of castings is still qualified.
4.6 The surface and appearance of castings shall be inspected piece by piece by visual inspection. The first and important castings shall be inspected piece by piece for size and geometry according to 3.5; general castings and castings produced by methods to ensure dimensional stability may be inspected randomly. The surface roughness of castings shall be inspected according to 3.7.1. If it does not meet the requirements, grinding and repair are allowed. 4.7 The weld repair of castings shall be inspected as follows according to the relevant provisions of JB/T6889: a. Cleaning of defective weld repairs; b. Weld repair method and welding rod used; c. Quality of defects after weld repair.
4.8 Castings that need to be tested for leakage according to the requirements of drawings, technical documents or order agreements shall be tested and inspected piece by piece according to 3.10.
5 Marking and Certificates
5.1 Qualified castings shall be marked by the manufacturer’s technical inspection department. The mark may be printed or painted (-…- generally, white paint shall be used to mark qualified products).
5.2 When castings are delivered to the warehouse or shipped out of the factory, they shall be accompanied by a product certificate that complies with this standard, which shall include: a. Name of supplier;
b. Name of casting;
c. Drawing number of casting, material grade and necessary inspection results; d. Manufacturing date (or serial number) or production batch number. 6 Rejection
6.1 Castings shall be rejected if they have external or internal defects and these defects have obvious damage to the processing properties and use properties measured according to the casting material and casting type. 6.2 The user must give the production unit an opportunity to confirm the rationality of the rejection. The rejected castings shall be kept by the supplier as much as possible before the formalities are handled.
222
Measuring surface height H
10
>10~40
>40～100
>100-~160
>160～~250
≥250~400
>400630
>630-1 000
>1 000~1 600
>1 600~2 500
>2500
z
255
1°25
0°40
0°30*
0*25
0°20*
0°15
JB/T 6887
Appendix A
93
Draft angle of wooden pattern for casting
(Supplement)
Table A1
Draft angle
Clay sand moulding
a
0. 6
1.0
1.2
1.4
1.8
3.0
3.8
5.8
9.2
11.0
Module
Oblique| |tt||degree
沁
2
4°00
2°05
0°55
0°40°
035
030
0°25
Self-hardening sand modeling
a
0.8
1.6||tt ||1.6
2.0
2.6
4. 2
5.6
7.4
11.6
18.2||tt ||mm
A1 For the machined surface and the non-machined side with a wall thickness less than 10mm, a "positive\slope" should be adopted; for the non-machined side with a wall thickness between 10~~30mm, the slope should be "positive and negative" ; Non-machined side surfaces with a wall thickness greater than 30mm should have a negative slope. A2 For the slope of the non-machined side that needs to be combined with other parts (such as the side connected to bolts), take half of the value in the table. A3 For difficult parts such as ribs, cast holes, and bosses, the value in the table can be doubled. 223
JB/T6887—93
Appendix B
Casting machining allowances used in conjunction with cast iron dimensional tolerances (GB/T1135089) supplement)
Table B1
Dimensional tolerance level CT
Machining allowance level MA
Basic size
greater than
100
160
250
400
630
1000
1600
2500
4000
6300
to|| tt||100
160
250
400
630
1000
1600
2500||tt| |4000
6300
10 000
8
3.0
2.5
4.0
3.5
5.0
4.5
6.5
6.0
7.5
7.0
8.5
8.0
10| |tt||9.0
11
10
13
12
9
3.5
3.0||tt ||4.5
4.0
5.5
5.0
7.0
6.0
7.5
7.0
9.0
8.0
11
9.5
12
11
14
12
15| |tt||13
10
4.0
3.0
5.0
4.0
6.0
5.0||tt ||7.5
6.5
8. 5
7.5
10
8.5
12
10||tt ||13
11
15
13
16
14
18
15
11
plus
4.5
3.5
5. 5
4.5
7.0
5.5
8.5
7. 0
9.5
8.0
11
9.0
13
10
14
12
16
13
18
15
20
16
12| |tt||H
Margin
5.0
3.5
6.5
5.0
8.0
6.0|| tt||9.5
7.5
11
8.5
13
10
15
12||tt| |17
13
19
15
21
16
24
18
13
Value
6.5
4. 5
8.0
5.5
9.5
7.0
11
8.0
13
9.5
T
15
11
17
13|| tt||20
15
22
16
25
18
28
20||tt| |14
7.5
5.0
9.
6.0
11
7.5
13
9.0
15
11
17
12
20
14
22
16| |tt||25
18
29
20
32
22
15
9.0||tt ||5. 5
11
7.0
13
8.5
15
10
17||tt ||12
20
14
23
16
26
18
29
20
33
22
37
25
mm
16
11
6.5| |tt||13
8.0
15
9.5
18
12
20
13||tt ||23
15
27
18
30
20
35
23
39
25
44
28
Note: There are two machining allowance values ??in each column of the table. The above values ??are based on one side. The allowance value for side machining; the following value is the machining allowance value for each side when double-sided machining is performed.
224
Basic size of castings
is larger than
10
16
25
40
63
100
160
250
400
630
1000
1600
2500|| tt||4000
6300
to
10
16
25
40
63||tt| |100
160
250
400
630
1000
1600
2500
4000
6300
10000
3
0.18
0.20
0.22
0.24
0.26|| tt||0.28
10.30
41
0.26
0.28
0.36
0.40
0.4
JB/T688793
Appendix C
Casting dimensional tolerance values ??(GB6414--86) ( Supplement)
Table C1
public
0.36
0.52
10.54
0. 38
0.58|| tt||62
0.34
10.500.70
0.40
0.56
0.64
0, 78
0 . 90
1.0
0.88
1.6
0.74
78
82
2.0
2.6
Difference
1.0
X
3
3.8
1.4
5.4
etc.|| tt||7.0
level
10
2.0
10
11
CT
11||tt| |2.8
12
14
16
12
4.2
4. 4
4.||tt ||JC
20
23
13
24
28
32
Note: CT13 to CT16 are less than Or when it is equal to the basic size of 16mm castings, the tolerance value needs to be marked separately and can be increased by 2 to 3 levels. Additional notes:
This standard is proposed and managed by the National Technical Committee for Fan Standardization. 30
35
40
15
10
22
38
50
mm| |tt||16
12
14
L
20
22
25
28||tt ||32
37
42
49
56
64
This standard is drafted by Shaanxi Blower Factory; Shanghai Blower Factory , Wuhan Blower Factory, Shenyang Blower Factory, Shenyang Foundry, and Chongqing General Machinery participated in the drafting.
The main drafters of this standard are Wang Kuiwang, Song Lili and Chaoyen. 225
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