Compilation of the enterprise standard for threaded fasteners for an engine

An engine is a product imported from the United Kingdom and manufactured by China. The structure is complex, the parts are numerous, and the process requirements are strict. The total number of single engine parts is more than 30,000 pieces, of which the total number of standard parts is 5,300, accounting for 15% of the total number of parts, including various varieties and specifications, and all are in English units.

The localization of the machine involves many units in China, and each unit involves the issue of threaded fasteners. Since the standard of threaded fasteners provided by foreign countries cannot meet the requirements of localization, new standards must be formulated as the basis for production and acceptance of the machine. To this end, the machine standardization system research decided to set up a standard preparation group to uniformly prepare threaded fasteners joint enterprise standards to standardize and unify the production of threaded fasteners of various units. The metallographic requirements for finished bolts are not clear.

3 Standard Compilation 3L1 Main Compilation Principle Threaded fasteners for engine interface parts must be used in English to ensure the interchange of Chinese and foreign models. Threaded fasteners in other parts are converted to metric.

According to the standards and technical data provided by the British side, under the premise of not reducing the British standard requirements and ensuring the product quality level, the current domestic standards should be adopted as much as possible, and prepared according to the CB/TL1 regulations.

For the technical content without domestic standards, when the standards are prepared, the technical level requirements are high, that is, the principle of “high or low”.

And acceptance. 2 Main problems existing before the standard preparation The technical requirements, raw materials, equipment, tooling and process used by each unit to produce threaded fasteners are inconsistent.

There are many varieties and specifications of threaded fasteners, small batch size and high cost.

The interchangeability of threaded fasteners is not good, and the acceptance and use are troublesome.

The same threaded fastener technical requirements are inconsistent.

Some general requirements for threaded fasteners, such as thickness of silver plating, general tolerances, heat treatment, non-destructive testing, mechanical testing items, inspection rules, etc. are inconsistent.

(6) The requirements for the metal flow line of the head bolt and the finished bolt flow line are not clear.

According to the actual needs of the production and acceptance of an engine main engine and auxiliary machinery factory, the 3L2 project determines the following joint enterprise standards.

Inch bolts General technical conditions Inch twelve-point bolts Inch twelve-point bolts (with steps) Inch twelve-point bolts Technical conditions Inch twelve-point self-locking nuts Inch twelve-point self-locking nut Technical conditions Engine-specific ordinary steel threaded screw engine Special locking type wire threaded sleeve engine special steel thread screw sleeve technical condition twelve-point bolt (metric system) revised draft 曰丨Revised draft period 2005-11-20Experience exchange Taikong cup Zhuneng twelve-point bolt technical condition ten Two-corner self-locking nut (metric) twelve-point self-locking nut technical condition 3L3 standard preparation technical problem in the preparation of the joint enterprise standard, the analysis and comparison of all the parts and models involved, the corresponding technical requirements and parts Inductive finishing, and strive to unify the size and materials as much as possible. For example, without using the requirements and quality, the same materials can be used, and the principle is uniform. The principle is that the height is not low. Uniform general tolerance requirements, individual requirements are adopted and executed according to hB5800. For the condition that the silver plating layer is not uniform, sub-standard processing is adopted. Measures; for the acceptance rules, the general technical conditions for the production of imperial and metric bolts, nuts and wire screws are uniformly formulated. In short, the content of the enterprise standards that are prepared to be compiled is harmonized, rigorous and scientific, and can ensure product quality.

In the process of joint enterprise standardization, the following technical problems are solved: silver plating layer problem: According to comparative analysis and performance considerations, the thickness of silver plating is divided into two types according to different thread specifications, that is, the thread size is less than or equal to 0i164 inches (4.166nm). Thread, silver plated thickness is (3~5)mm thread size is larger than ai64 inch thread, silver plated layer thickness is (58)mn. Size, dimensional tolerance, shape tolerance problem: tolerance in original product pattern Inconsistent requirements, some requirements according to the US standards, some requirements according to the British company's technical conditions standards preparation group through the comparative analysis of national standards, industry standards and the relevant documents of the British, in order to ensure product quality adopted "high or low" the rules.

Materials, heat treatment and other issues: On the basis of analysis and comparison of the British and Chinese standards and related materials, CB2294 and corporate standards are implemented in accordance with the standard compilation principles.

(4 The joint enterprise standard puts requirements on the metal flow line of the bolt head and the metal flow line of the finished bolt in the form of illustration and text, and gives a schematic diagram.

In order to ensure the quality of the cold rolling adapter arc, different heat treatment conditions are specified for the bolts made of different materials before cold rolling.

The following metallographic requirements are imposed on the finished bolts: surface contamination requirements for different parts of the bolt; grain size requirements for various parts of the finished product bolts; low-corrosion defects and overheating requirements for the longitudinal profile of the finished bolts.

The non-destructive testing standard for finished bolts is specified.

The mechanical properties test items such as hardness and tensile force are specified, and the acceptance test is specified.

Inspection rule problem: Due to the inconsistency of the requirements of the British standard and technical documents, the operability of the product acceptance is very poor. Therefore, the general technical conditions of the British bolts, the technical requirements of the inch twelve-point bolt and the inch twelve-point self-locking nut are prepared. 6 metric metric bolts and metric 12-point self-locking nuts and technical specifications for engine-specific wire thread inserts, which are controlled by various types of bolts and nuts, and are controlled by Professional manufacturers produce to ensure the variety, quantity and quality of the products and interchangeability, but also facilitate the production and acceptance of the production plant.

The test requirements, methods and inspection rules of the wire screw sleeve are given, such as: nut for locking torque test, test piece, locking test speed, durability test, vibration test, identification and acceptance, batch acceptance.

The minimum breaking load was calculated and confirmed, and the roughness requirements of the chamfering, empty sipe, and fuse hole surface were increased: 3 mm).

4 Standard characteristics The characteristics of 22 joint enterprise standards for an engine are: including public and English systems, eliminating the problem of inconsistency between domestic and foreign standards; without lowering the original British standard and ensuring product quality Under the premise, the domestically produced materials are fully adopted; the content is comprehensive, coordinated and convenient, easy to use, strong in operability, large in scope of application, and has certain promotion and use value.

5 Conclusion 22 threaded fasteners and wire threaded joints have been analyzed for 4 years after use. Our company has analyzed and researched the problems. Finally, it is revised to become a practical and applicable screw tightening for an engine. The joint enterprise standard lasted for nearly seven years.

The standard content is large, the scope is wide, and the preparation is difficult. The compilation team has carefully analyzed and contrasted the British standards and found the marking entry points, especially the technical indicators such as the strength and axial load of the substitute fasteners. Computational and comparative analysis In-depth research on how to eliminate difficult process problems such as thread folding ensures that the performance indicators in the joint enterprise standard are not lower than the requirements of the original British standard. It has been verified by experiments that 22 joint enterprise standards are safe, reliable and practical, and can guarantee product quality.

Up to now, there have been actual installed flights of batch engines. It has been proved that 22 joint enterprises have all the quality problems and can meet the military requirements. This series has been awarded to the level of similar foreign countries. %r.(Editor: Gan Lin) Experience Exchange

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