GB/T 2785-1988 Technical Specifications for Valve Springs for Internal Combustion Engines GB/T2785-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Technical conditions for valve springs for internal combustion engines
Internal combustion engines—Valve springs-SpecificationSubject content and scope of application
This standard specifies the technical requirements, test methods and inspection rules for valve springs. GB 2785-88
Replaces GB2785-81
This standard applies to valve springs for small and medium-power internal combustion engines with a cylinder diameter of less than or equal to 200mm (hereinafter referred to as springs). 2 Reference standards
GB1239 Ordinary cylindrical helical springs
GB1805 Spring terminology
GB4358 Music wire
GB 4359
GB 5220
GB2271
GB4362
GB 2828
JB/Z 255
3 Technical requirements
Oil quenched and tempered carbon spring steel wire for valves Chrome vanadium spring steel wire for valves
Oil quenched and tempered chrome vanadium alloy spring steel wire
Oil quenched and tempered chrome silicon alloy steel wire for valves Rockwell hardness test method for metals
Decarburization depth test method for steel
Count sampling procedure and sampling table for batch inspection (applicable to inspection of continuous batches) Technical specifications for shot peening of cylindrical helical springs
3.1 Products shall comply with the requirements of this standard and be manufactured according to product drawings and technical documents approved by the prescribed procedures. 3.2 The form of the spring is a cylindrical helical compression spring with round cross-section, with both ends tightened and ground flat. The pitch of the spring is divided into two types: equal pitch and unequal pitch.
3.3 Materials
3.3.1 Springs should generally be made of spring steel wire listed in Table 1, or they can be made of spring steel wire of other requirements agreed upon by both parties. 3.3.2 The diameter d of the spring steel wire shall be in accordance with the provisions of Table 2, and the first series shall be preferred. 3.3.3 The spring steel wire shall comply with the relevant provisions of the national standards listed in Table 1. 3.3.4 The spring steel wire must have a quality inspection certificate issued by the material manufacturer, and can only be used after being re-inspected and qualified by the spring manufacturer. Table 1
GB4358
GB34359
Piano wire G Group, Gz Group, F Group
Oil quenched carbon spring steel wire for valves
Approved by the State Machinery Industry Commission on 1985-05-13 236
60, 70, 80, 60Mn, 70Mn, T8MnA, 65, 75, 65Mn.T9A
Implemented on 1989-01-01
GB5220
GR2271
GB4362
Series
No. Series 2
3.4 ​​Heat treatment
Alloy spring steel wire for valves
GB2785—88
Continued Table 1
Oil-quenched chrome-vanadium alloy spring steel wire for valvesOil-quenched chrome-silicon alloy spring steel wire for valvesTable 2
50CrVA
50CrVA
55CrSi
Springs made of annealed steel wire must be quenched and tempered. The number of quenching times shall not exceed 2 times, and the number of tempering times is unlimited. Springs made of steel wire that does not require quenching must be tempered. 3.4.1 Hardness
After quenching and tempering, the hardness value of springs made of annealed steel wire should be selected within the range of HRC44~50, and the hardness difference of the same batch of springs should be less than or equal to 5 HRC units. The hardness value of springs made of steel wire that does not require quenching treatment is not subject to assessment. The hardness value of springs treated by isothermal quenching should be selected within the range of HRC46-54, and the hardness difference of the same batch of springs should be less than or equal to 5 HRC units. 3.4.2 Metallographic structure
The metallographic structure of springs treated by quenching and tempering should be tempered troostite, with a small amount of troostite allowed, and martensite is not allowed. The metallographic structure of springs treated by isothermal quenching is lower bainite and tempered martensite. 3.4.3 Decarburization
For cold-rolled springs treated by quenching and tempering, the depth of the decarburization layer on one side is allowed to increase by 0.25% of the material diameter compared with the depth of the decarburization layer specified in the raw material standard.
3.5 Dimensional deviation and geometric tolerance of springs
3.5.1 The deviation of the outer diameter or inner diameter of the spring is ±1% of the median diameter, and the tolerance of the outer diameter or inner diameter of the support rings at both ends is 1.5% of the median diameter. 3.5.2 The spring free height deviation is ±2% of the free height. When the product drawing specifies the spring load at two points, valve closed and valve fully open, the free height is not subject to assessment.
3.5.3 When the spring is in the free state, the perpendicularity of the outer circle element line to the supporting surfaces at both ends shall be less than or equal to 2.5% of the free height. 3.6 Parameter adjustment
The spring manufacturer needs to make production adjustments to meet the specified spring load requirements. The parameters that can be adjusted are listed in Table 3. Table 3
Specified parameters
Spring load and corresponding spring height
Spring load, corresponding spring height and H
Measure the spring load at two points and the corresponding spring height H. bzxZ.net
Parameters allowed for adjustment
n and d or n and D, D, (D,)
Ho, n and d or Ho, n and D.Di (D,)
Note: The parameter values ​​adjusted during manufacturing should be indicated on the drawing, but they are only for reference. 3.7 The difference between the total number of spring turns and the number of working turns should be greater than or equal to 2 turns. The two support rings should be ground, and the ground flat part should be greater than or equal to 3/4 of the circumference of the end ring, and the surface roughness R. should not be greater than 6.3um. There should be no burrs and sharp edges, and the end thickness should be greater than or equal to 1/8 of the wire diameter.
3.8 The deviation of the spring load P, when the valve is closed is P, ± 8%, and the deviation of the load P when the valve is fully open is P2 ± 5%. 237
GB2785—88
3.9 The spring shall be subjected to non-destructive testing, which shall be carried out before shot peening. After magnetic testing, the spring shall be demagnetized. 3.10 The spring shall be subjected to shot peening treatment, and the surface coverage of the shot peening shall be greater than or equal to 90%. The shot peening intensity shall be selected in the range of 0.15A to 0.60A.
3.11 After the spring is compressed to the working limit position or the circles are in contact, its permanent deformation shall be less than or equal to 0.3% of the free height. 3.12 After the spring is subjected to 1×10° cycle test, it is not allowed to break, and the loss of load P2 shall be less than or equal to 5% of P2. 3.13 The spring shall be subjected to surface anti-corrosion treatment.
4 Test method
4.1 Permanent deformation
It is carried out on a spring testing machine. The spring is compressed briefly three times. The compressed height is the working limit height or the tightening height. The maximum tightening load shall not exceed 1.5 times the theoretical compression load. The change in the free height of the spring before and after compression is measured. 4.2 The inspection of the load deviation of the finished spring is carried out after measuring the permanent deformation. The spring load is carried out on a spring testing machine with an accuracy of 1%. The test height is specified in the product drawing. The springs classified by load are tested according to the groups they are divided into. 4.3 Spring diameter
Measured with a vernier caliper with a graduation value less than or equal to 0.02mm. The outer diameter is measured if the outer diameter or middle diameter is indicated on the drawing, and the inner diameter is measured if the inner diameter is indicated.
4.4 Free height of the spring
Measure the highest point with a vernier caliper with a graduation value less than or equal to 0.02mm. 4.5 Verticality of the supporting surfaces of the two ends of the outer circle of the spring. Place the spring vertically on a second-level precision flat plate and measure it with a third-level precision wide-seat angle ruler. After rotating the spring on the wide-seat angle ruler for one circle, check the other end (the second adjacent circle is tested from the end to 1/2 circle), and use a 100mm feeler gauge to measure the maximum deviation of the verticality. 4.6 The hardness test of the spring shall be in accordance with the provisions of GB230. 4.7 The depth test of the decarburized layer of the spring shall be in accordance with the provisions of GB224. 4.8 The surface and shot peening coverage of the spring shall be inspected with a tool microscope or a five-fold magnifying glass. 4.9 Shot peening treatment
4.9.1 The shot peening intensity is measured by a single-sided A-type shot peening test piece and a measuring tool based on the curvature generated on the test piece. 4.9.2 The shot peening coverage is expressed as a percentage of the surface area actually impacted by the shot peening to the surface area of ​​the spring sprayed. 4.10 When the spring is subjected to fatigue test, the number of tests shall be greater than or equal to the springs used in the set of internal combustion engines. No fracture is allowed after 1×10° stress cycle. The load borne by the spring must be consistent with the actual working conditions. 4.11 The spring should be subjected to reliability test. The test time is equal to the engine warranty period. 5 Inspection rules
5.1 The permanent deformation of the spring shall be in accordance with the provisions of Article 3.11. 5.2 The diameter inspection of the spring shall be in accordance with the provisions of Article 3.5.1. 5.3 The free height inspection of the spring shall be in accordance with the provisions of Article 3.5.2. 5.4 The verticality inspection of the outer circle of the spring to the supporting surfaces at both ends shall be in accordance with the provisions of Article 3.5.3. 5.5 The load inspection of the spring shall be in accordance with the provisions of Article 3.8. 5.6 The inspection of spring surface shot peening coverage shall be in accordance with the provisions of Article 3.10, and the inspection method shall be in accordance with the provisions of JB/Z255. 5.7 The inspection of spring material quality shall be in accordance with the provisions of Article 3.3.3. 5.8 The inspection of spring hardness shall be in accordance with the provisions of Article 3.4.1. 5.9 The inspection of the decarburization layer depth of the spring shall be in accordance with the provisions of Article 3.4.3. 5.10 The spring manufacturer shall regularly (at least once a year) conduct fatigue tests on the finished springs and inspect them in accordance with the provisions of Article 3.12. 5.11 When the ordering unit conducts sampling acceptance inspection on the batch-produced springs, it shall be in accordance with the provisions of GB2828, and the qualified quality level and sampling plan shall be in accordance with the provisions of the contract between the supply and demand parties. 5.12 The following items should be checked for springs:
GB2785--88
Defect items: fatigue test, metallographic structure, decarburization, hardness: a.
Defect items: permanent deformation, load P2, shot peening coverage;,
Defect items: spring diameter, verticality, load P2, surface defects. 6 Marking, packaging, transportation, purchase and storage
6.1 Products should be cleaned and rust-proofed before packaging, and wrapped with strong and impermeable paper or put into plastic bags and then packed into cardboard boxes. Each box should contain springs of the same model. The packaging box should be marked with: a.
Manufacturer name, trademark and address;
Product name and model,
Quantity:
Date of sale.
6.2 The box should be accompanied by a product certificate inspected by the inspector of the manufacturing and inspection department. 6.3 Products packed in cartons should be packed in sturdy packaging boxes with moisture-proof performance. The packaging boxes should ensure that they will not be damaged during normal transportation. The total mass of the box should be less than or equal to 50kg
6.4 The packaging box should be accompanied by a packing list, which should indicate the product name, model and factory date. The outside of the package should indicate: the shipping address and the name of the receiving unit:
Product name and model,
Gross weight,k*
Manufacturer name, trademark and address:
"Handle with care" and "Moisture-proof" and other words and symbols,f. Expiration date.
6.5 Products should be stored in a ventilated and dry warehouse. Under normal storage conditions, the manufacturer should ensure that the products will not rust within 12 months from the date of leaving the factory.
6.6 Springs supporting the main machine can be transported in container packaging. The container should be firmly divided to prevent collision. The technical conditions of container packaging shall be agreed upon by the manufacturer and the user.
Total number of turns n=
Heat treatment hardness HRC
Shot peening strength A
Spring sleeve DT
GB 2785-88
Appendix A
Drawing form
(reference)
Technical requirements
Working number of turns n=
Surface coverage
Spring mandrel D
Vertical degree of outer circle element line to the supporting surfaces at both ends Surface anti-corrosion treatment
Unfolded length
Other special requirements
The rest shall be in accordance with GB2785-88 "Technical Conditions for Valve Springs for Internal Combustion Engines" Specified working conditions and design parameters
Spring operating frequency f
Spring natural frequency
Deformation when valve closed
Deformation when valve fully open -
GB278588
Deformation when working limit deformation is high - stress ()
Evaluated average stress
Stress amplitude a
Cycle characteristic coefficient
Note: 0 Two spring diameters can be reported according to the need to indicate one. D can be specified according to the need to indicate the type or all of the head.
③ Material properties must indicate the material diameter, body number and mark number. Additional remarks:
This standard is under the jurisdiction of Shanghai Internal Combustion Engine Research Institute. This standard is drafted by China Spring Factory. Pa
This standard refers to the Federal German standard DIN2095-73 "Quality Specification for Cold-wound Compression Springs Made of Round Wire Cylindrical Helical Springs".
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