GOST 7829-70

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  ГОСТ 7829-70

GOST 7829−70 Forgings from carbon and alloy steel, fabricated by hammer forging. Allowances and tolerances (Change No. 1)

GOST 7829−70

Group B03

INTERSTATE STANDARD

FORGINGS FROM CARBON AND ALLOY STEEL,
FABRICATED BY HAMMER FORGING

Allowances and tolerances

Cardon and alloyed steel forgings fabricated by hammer forging.
Allowances and tolerances

ISS 77.140.85
OKP 08 9300

Date of introduction 1971−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of heavy and transport engineering

2. APPROVED AND put INTO EFFECT by Decision of the Committee of standards, measures and measuring devices under Council of Ministers of the USSR from 15.01.70 N 60

3. REPLACE GOST 7829−55

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

6. EDITION (December 2003) with amendment No. 1, approved in October 1987 (ICS 1−88)

1. This standard applies to forgings for General purposes, manufactured from carbon steel and alloy steel forging hammers with single and small batch production, and sets the size of the machining allowances of cutting, the value of the maximum deviations on the nominal dimensions of forgings, as well as the amount and conditions of appointment of overlaps for forgings.

The standard does not apply to forgings of high-alloy steels and alloys with special physical properties.

Special allowances on samples for mechanical testing, clamps for hanging them during heat treatment and for other technological purposes standard not set.

(Changed edition, Rev. N 1).

2. The shape and ratio of the size of forgings that are covered by this standard are shown in table.1.

3. Allowed the sphericity of the ends of the forgings that are made by the hood when there is trubka, the sphericity of the side surface of the forgings that are made by the draught, and also bevels between the ledges, Cocina Ruba at the ends, the taper or slope in the hole in the limits table.2 and 7−13.

4. The allowances established by this standard are assigned to the nominal dimensions of a part or pre-treated (stripped) of the workpiece, if the forging is subjected to heat treatment after the roughing.

Table 1

_______________
* Equipment for manufacture of forgings of the type of plugs with ledges is selected at the discretion of the manufacturer in terms of economic feasibility.


(Changed edition, Rev. N 1).

5. The scheme of allowances that are assigned to the outer dimensions of the part, and extreme deviations from the nominal size of forgings is shown in hell.1.

 — rough blank size or the nominal size of the part;  — the minimum stock size ;

 — nominal allowance for size ;

;

 — the minimum size of forgings:

;

 — nominal (calculated) size of forgings:

;

 — the maximum size of forgings:

;

 — the limit of deviation of the size of forgings

.

Damn.1

6. The magnitude of the allowances prescribed by this standard, should be assigned to the nominal dimensions of the parts in the calculation of the machining of forgings on both sides.

Maximum deviations are established on the nominal dimensions of the forgings.

7. Machined surfaces of the parts allowance should not be appointed, and the magnitude of extreme deviations should be determined by the tables of this standard depending on the type and dimensions of the forgings.

8. For parts to be processed on the one hand, the amount of the allowance is taken with a factor of 0.5 from table values. The magnitude of extreme deviations it should be taken as equal to the tabular values.

9. Allowances and limit deviations governed by this standard, established for the case of the manufacture of forgings from rolled steel or stripped of the ingot. When forging from ingot neurogennogo allowed to increase the allowance for a value of not more than 20% of the table value of allowances.

10. By agreement between manufacturer and consumer, it is possible the tightening of allowances, limit deviations and overlaps.

(Changed edition, Rev. N 1).

11. Allowed to round the calculated nominal dimensions of the forging to the nearest whole number in a big way.

12. The volume and weight of the forgings be determined based on their nominal dimensions, taking account of the overlaps on the slopes between the ledges, for bevel cuts, on the sphere and the taper hole.

13. Bevels from otrubki forgings must be free of burrs and must not interfere with the alignment.

14. Allowances and limit deviations for smooth forgings with round, square and rectangular section with length up to 6000 mm should be assigned in accordance with the devil.2 and table 2.

Damn.2

Table 2

mm

Notes:

1. In the case of processing the surface of the part at the 4th and higher purity grade may be increased to a corresponding table value of allowances, but not more than 1 mm on a side.

2. Allowances and limit deviations for rectangular items are assigned depending on the largest dimension of the cross section.

(Changed edition, Rev. N 1).

15. Allowances and limit deviations for forgings of round and square cross-sections with ledges appointed basic and advanced.

Basic allowances and limit deviations should be appointed in accordance with the devil.3, tab.2 and the following requirements:

allowance and deviations in the diameter and size of the cross section is prescribed in table.2 depending on the total part length and diameter or dimension of the considered cross-section;

allowance for the total length of the part accept is 2.5 allowances on the diameter or size of the projection of the greatest cross-section;

maximum deviations for the total length of the part accept is 2.5 deviations on the diameter or size of the projection of the greatest cross-section;

allowances on length of ledges and ledges accept multiple of the allowance at the diameter or size of the protrusion section according to greatest features.3. While the length of the ledges and recesses in the drawing, forgings point from a single database. For the base accept the end of the projection of the greatest cross-section is not a end of the forging;

limit deviations of the length of the ledges and overhangs are equal to 1.5 deviations of the diameter or size of the protrusion section according to greatest features.3;

if the length between the notches before the forging of the recesses is less than the width of the striker is permitted, the increase in allowance and the limiting variance of 10% against the values table.2.

Damn.3

Additional allowance should be given according table.3 on the diameters (sizes) of all sections, except the main one, depending on the difference of the diameters (sizes) and see the most cuts, with the appointed main allowances.

Table 3

mm

The main section should be determined in the following order:

a) if the forging has a step from the machined surface for the main section take the stage with uncultivated surface;

b) if the forging does not have steps machined surface, in order to determine the main counting section area of the longitudinal sections of steps ; ; … and compare them with the square longitudinal cross-section of the projection with the largest diameter ;

if all the received values ; ; …less than , then for the main section, take the ledge with the greatest diameter;

if there is values ; ; …more than that , for those values of ; ; …more , counting value

*;

* etc.

and the main section take the section for which value has the highest value;

if the main section is not adopted the protrusion of the greatest diameter , the additional allowance is transferred from the primary section to the ledge of the greatest diameter.

________________
* Formulas correspond to the original. — Note the CODE.

An example of assignment of allowances and the marginal variance is given in Appendix (example 1).

16. The feasibility of the forging of end and intermediate ledges (Fig.4), seizures (Fig.5), flanges (DWG.7a) and clamps (Fig.7b) check after assigning the basic and additional allowances in accordance with table.4 subject to the following requirements:

Table 4

mm

a) end and intermediate ledges (Fig.4) is performed if their height ; ; ;… not less than the values given in table.4, and if their length ; ; with respect to the width of the striker is not less than the value specified in table.5;

Table 5

mm

At the same time:

if the height of ; ; ;… ledge less than the values shown in table.4, the ledge must be forged by the diameter of the adjacent ledge;

if the length of the ledge is less than the values given in table.5, it must be forged in the case where the amount of overlap when you bring it to a workable length is less than the amount of overlap when chipping off its diameter adjacent the ledge;

b) a recess (Fig.5) is performed, if the length between the notches (Fig.6) before the forging of the recesses in relation to the width of the striker is not less than the value specified in table.6;

Table 6

mm

if the length of the plot forgings, pricekamagra to perform excavation, less than specified in table.6, the diameter of the recess appoint the slouchy fit of the calculation to the length of presecki was equal to the corresponding value table.6;

in) flange (DWG.7a) perform, if its length is more than the height of the ledge , taken with coefficient of 1.2, but at least 0.2;

if the length of the flange is less than the height of the ledge , taken with coefficient of 1.2 or less than 0.2, then the length of the flange is adjusted to a feasible size due to the inlet or from the end or side of the ledge, proceeding from conditions of the minimum amount of overlap;

g) Burt (damn.7b) perform, if its length is more than the height of the lower adjacent ledge, but not less than 0.2;

if the length of pile less than the height of the lower surrounding ledge, or less than 0.2, then the length of the collar is adjusted to a feasible size due to the inlet by any of the ends from the condition that the amount of overlap was minimal.

Damn.4

Damn.5

Damn.6

Damn.7

An example of determining the feasibility of ledges, recesses, clamps and flanges are given in Appendix (example 1).

17. Allowances and limit deviations for forgings such as disks, cylinders, bushings, bars, cubes, plates and solid discs, sleeves, bars, plates with holes should be appointed in accordance with the devil.8 and table.7.

Damn.8

Table 7

mm

Notes:

1. On cylindrical forgings having the ratio of the diameter to the height of more than 6 allowed sphericity, the value of which is not controlled.

2. You don’t need to flash the hole with a diameter of 40 mm and when the ratio of the height of the forging to the diameter of drilled holes .

3. In the bore of the forgings in excess of the allowances allowed slope of 1:20.

4. (Deleted, Rev. N 1).

5. Allowances and limit deviations for rectangular cross-section details is prescribed depending on the largest dimension of the cross section.

(Changed edition, Rev. N 1).


An example of assignment of allowances and the marginal variance is given in Appendix (example 2).

18. Allowances and limit deviations for forging such as rolled rings should be appointed in accordance with the devil.9 and table.8.

Damn.9

Table 8

mm

Note. In the hole in addition to the allowances permitted conicity of 1:20.


An example of assignment of allowances and the marginal variance is given in Appendix (example 3).

19. Allowances and limit deviations for forgings such as cylinder with a hole should be assigned in accordance with the devil.10 and table.9.

Damn.10

Table 9

mm

________________