RU2554243C1 - Production of collapsible article consisting of two mating parts - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: first part is made and mating surfaces are measured. Computer model of second part is constructed. Mating surfaces of said part are simulated with due allowance for the results of aforesaid measurements. Control programme is developed for machine tool equipped with NC control system to produce said second part. First and second parts are assembled and obtained joint is controlled.

EFFECT: higher precision of parts mating, lower labour input.

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Description

The method can be used to improve the quality of assembly of mechanical engineering parts in conditions of both small-scale, serial and mass production types.

Various methods for assembling parts are known in the art. With regard to mass and mass production, the assembly method with full interchangeability has become widespread (A. Kovshov, Engineering Technology. Pp. 186-191). When using this method, a high-quality connection is formed by any mating parts included in the assembly unit. The method can be implemented if the tolerance of the closing link is calculated by the limit values of the tolerance on the dimensions of the component links [1].

However, this method is economically disadvantageous for multi-link dimensional chains, since it leads to the necessity of assigning very tight tolerances on the dimensions of the component links.

The closest in technical essence to the proposed technical solution and providing high-quality mating of parts are various methods of grinding parts, while the assembly is carried out on the basis of the method of incomplete interchangeability, in which the tolerances on the dimensions of parts that make up the dimensional chain are deliberately expanded.

Known, for example, is the method of mutual grinding in of mates (a.s. 846235 USSR, IPC V24V 15/08, publ. 07/25/1981), which consists in the fact that the mating parts are pressed against each other, while one of them is reported to rotate, and another set motionless. The clamping force of a rotating part is chosen equal to the clamping force of the mating parts when operating them in a machine assembly [2].

There is a method of ensuring interchangeability when grinding mating parts (a.s. 701768 USSR, IPC V24V 1/00, V24V 15/08, publ. 07.12.1979), in which a series of sequential operations are performed for mutually grinding pairs of parts with separation, mixing, random and equally probable pairwise picking before each subsequent grinding operation [3].

The disadvantages of these methods are fully manifested in situations where it is necessary to ensure the required quality of the interface simultaneously on several surfaces. These include, in particular, interfacing with a complex multi-stage circuit with functionally interconnected surfaces. As a result, lapping of one pair of surfaces according to the required indicator of the accuracy of mating entails a change (decrease) in the accuracy indicators for other pairs of surfaces of the same mating. At the same time, the complexity of control operations also increases significantly.

The objective of the claimed invention is to develop a method that improves the accuracy of mating while reducing the complexity of the mechanical processing of the mating surfaces of the parts.

This problem is solved due to the fact that the proposed method includes the manufacture of the first part, the measurement of its surfaces mating with the second part, which ensures the functional purpose of the interface, the creation of a computer model of the second part, and its surfaces mating with the first part are modeled taking into account the results of the measurement, manufacturing the second part on the machine with numerical control according to the control program developed on the basis of the mentioned computer model, and the assembly the first and second parts with control of the obtained pairing.

The invention is illustrated by drawings, which respectively show the sketches of the mating parts (Fig. 1, Fig. 2), and structural diagrams of the technological processes of their manufacture by the traditional grinding method and the proposed method (Fig. 3, Fig. 4).

The proposed method is as follows:

- make the first of the pairing parts;

- perform the control operation of the first part and measure its mating surfaces, ensuring the implementation of the functional purpose of the mate (while taking into account possible deviations of the shape and size of the surfaces from the requirements given in the design documentation);

- create a computer model of the second mating part, while the mating surfaces of the second part are modeled taking into account previous measurements of similar surfaces of the first part;

- develop a control program for processing the second part of the interface on the machine with a system of numerical control;

- make the second pairing;

- perform the operation of assembling parts;

- perform the operation of monitoring the resulting pairing.

The implementation of the method will be considered on the example of the assembly of two parts included in the assembly unit (Fig. 1, Fig. 2). At the same time, the following technical requirements are presented to the latter: to ensure smoothness and accuracy of mutual movement of parts along the groove, ensuring a clearance on side 4 of not more than 0.05 mm, an adherence density of the second part to surface 1 of at least 75%, the clearance in the interface 2 should not exceed 0.15 mm, and the difference in planes 3 is not more than 0.05 mm.

The traditional technology in the manufacture of these parts involves the use of the fitting operation, the need for which is due, in particular, to the low rigidity of the parts and the occurrence of deformations after heat treatment.

To check the real relative position of the parts and the nature of the mating, we measured the mating surfaces in products made by traditional technology and recognized as suitable. Based on the measurement results, a gap field was constructed in conjunction. The analysis of the gap field showed that the real gaps exceed the permissible value by 1.2 ... 1.8 times.

The traditional technological process of machining part 2 provides the following requirements: smallest roughness Ra = 6.3 μm, perpendicular tolerance 0.05 mm, flatness 0.2 mm, symmetry 0.025 mm, path tolerance 0.2 mm. The technological process in this case includes the following steps (Fig. 3): manufacturing of part 1 with a total laboriousness of machining operations of 5 hours (D ₁ ); control of part 1 with a complexity of 0.2 hours (KD ₂ ); manufacture of part 2 with a total laboriousness of machining operations of 1.2 hours (D ₂ ); control of part 2 with a complexity of 0.1 hours (KD ₂ ); the fitting fit operation of part 2 with a laboriousness of 0.5 hours (DM ₂ ).

The technological process of the proposed method can significantly reduce the amount of fitting work, replace the twenty-seven technological operations required for the manufacture of part 2, with one control and measuring operation (IES ₁ ), during which the interface elements of part 1 are controlled and a computer model of part 2 is created taking into account the measurements taken, and four machining operations on a machine with numerical control. The technological process according to the proposed method includes the following steps (Fig. 4): manufacturing of part 1 with a total laboriousness of machining operations of 5 hours (D ₁ ); control and measuring operation (KES ₁ ), including the control of the interface elements of part 1 and the creation of a computer model of part 2, the complexity of 0.05 hours; the manufacture of part 2 on a machine with numerical control with a total complexity of technological operations of 0.6 hours (D ₂ ); control of part 2 with a complexity of 0.1 hours (KD ₂ ); the fitting fit operation of part 2 with a laboriousness of 0.1 hours (DM ₂ ). As a result, the application of the manufacturing process for manufacturing parts 1 and 2 according to the proposed method allows to reduce the complexity of manufacturing parts 2 by more than 56% (i.e., T ₂ ≈0.5T ₁ ), which reduces its cost by 30%.

Preliminary economic calculations show that if the release program for the product discussed above is 63,300 units. per year, the reduction in the complexity of the introduction of the technological process by the proposed method will exceed 60 thousand hours. Moreover, the calculation does not take into account the effect of reducing the complexity of part 1 due to the presentation of less stringent requirements for the accuracy of its size.

In general, a positive technical result from the application of the method described above is to increase the accuracy of mating parts in the manufacture of prefabricated products, significantly expanding the variety of machining operations that can be used to process the first of the mating surfaces while significantly reducing their complexity.

Information sources

1. Kovshov A.N. Engineering Technology: A textbook for students of engineering specialties of universities. - M.: Mechanical Engineering, 1987. - 320 p.: Ill.

2. A.S. 846235 USSR, IPC V24V 15/08. The method of mutual grinding of mates / Yu.P. Kholmogortsev, A.P. Kramarenko. Publ. 07/25/1981. Bull. No. 26. 2 s.: - 1 ill.

3. A.S. 701768 USSR, IPC V24V 1/00, V24V 15/08. The way to ensure interchangeability when grinding the mating parts / B.V. Birin, M.I. Pepper, S.S. Rosenberg Publ. 12/07/1979. Bull. No. 45. 4 p.: - 3 ill.

Claims (1)

A method of manufacturing a prefabricated product consisting of two mating parts, including manufacturing the first part, measuring its surfaces mating with the second part, providing mating functionality, creating a computer model of the second part, and its surfaces mating with the first part are modeled taking into account the results of said measurement, the manufacture of the second part on a machine with numerical control according to the control program developed on the basis of the above-mentioned computer model, and the assembly of the first and second parts with the control of the resulting interface.

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