Method for interference fit of parts

FIELD: machine building.

SUBSTANCE: invention is related to machine building and instrument making, and may be used in performance of machine assembly works. Method for interference fit of parts by means of press fitting with application of material that strengthens the joint includes partial press fitting of parts with measurement of press fitting force and their further additional press fitting. According to method partial press fitting of parts is carried out. Then material that strengthens joint is applied on free sections of joined surfaces of one or both parts. After that their further additional press fitting is realised.

EFFECT: simplification of assembly process and reduction of costs for joint strengthening.

2 dwg

 

The proposed method relates to machine building and instrument engineering and can be applied when performing Assembly work, in particular, when connecting parts with tension.

A known method of monitoring the strength of the connection tightness by measuring the force of pressing parts [1, s].

There is a method of joining parts with tension, which for hardening compound prior to Assembly on the joined surfaces apply a binder, reinforcing materials, for example, electroplating coatings, adhesives or polymer, in particular anaerobic, materials [1, s, 2, p.116, 142, 3]. The disadvantage of this method is that the materials applied in the Assembly of all of the connections made in accordance with the standard fitted tightly, not taking into account that the tightness within one planting is changed several times. In this connection, with average and high level of tightness, can be reliably transmit operational loading, and their hardening is irrational, as it leads to additional costs. In addition, some compounds sufficient to cause hardening material on a limited part of the articulating surfaces, which will also lead to additional savings when implementing method.

Known the closest in technical essence is "the Way of the connection details" [4], to the torus to strengthen the connection carry out a partial pressing parts nedoresova to the end position of 0.3-1.0 mm and the subsequent finish pressing in vacuum with the speed 12-900 m/min However, this method is primarily meant for compounds obtained by heating or cooling the parts to be assembled, and difficult to implement as it involves the use of vacuum equipment and special pressing equipment. In addition, it also involves the strengthening of all connections, including those that have the necessary operational strength.

The technical result of the proposed method is a simplification of the process of Assembly of the parts and reducing the cost of strengthening the connection.

The essence of the proposed method lies in the fact that you are doing a partial pressing parts with measurement efforts pressing and then the finish pressing, thus causing a hardening compound material. According to the present invention will first do a partial press-fitting the parts, then on free sites connected surfaces of one or both parts cause hardening compound material, followed by their subsequent finish pressing.

The moment when you have to apply a hardening compound material, determine, for example, by measuring the force pressing the TCand comparing it with a preset value associated with the maximum shear load acting on the connection during its operation. While this comparison may occur in the ü situation, when the reinforcing material is applied is not necessary, i.e. the connection has sufficient strength and hardening, is not required.

This combination of new and known characteristics allows us to simplify the Assembly process and hardening compounds, compared with the closest analogue, as it does not require evacuation, zone of contact and finish pressing the connection with great speed. In addition, significantly reduced the cost of hardening compounds, as only strengthened the connection, which with high probability will not be able to transfer operational loading without hardening, and for a number of compounds, the material is applied only to a relatively small part of the area of the connection.

In particular, it is proposed reinforcing material is applied when the force pressing takes the value

where: TCthe force pressing; Te- maximum shear load acting on the connection during its operation; n is the factor of safety connections normally associated with the design, depending on the responsibility of the connection within n=1,1...2,5 (it is prescribed to compensate for possible errors in determining the operation load and the dynamic action and other factors that affect the strength of the connection is Oia and unaccounted for in the formula (1) [5, p.20; 6, pp. 102]); l1- the length of the connection tightness; l is the length of the partial pressing of the parts, and then put a hardening compound material.

The proposed method is illustrated in the drawings. Figure 1 shows the scheme of its implementation. Figure 2 shows graphs illustrating the relation (1).

Figure 1 shows a partial pressing of the connection tightness with a bore diameter D to the length of the partial fitting parts l with a force of pressing the TC(the length of the connection after additional pressurizing - l1). If TCfor example, take the value that satisfies the relation (1), the free portions of the joined surfaces of the shaft 1 and/or sleeve 2 is applied reinforcing the connection material. Then the connection zapressovyvajut to the end position, when the coupling length becomes equal to l1.

Figure 2 shows the dependence of the force pressing the TCthe length of the partial pressing of parts l, is divided into m=10 control points (tenth point corresponds to the length of the connection l1). To connect with the force pressing(2) ratio (1) throughout the process of pressing is not performed, so the padding is impractical and the material is not applied. To connect with the force pressingat the point m=6 is the ratio of (1), indicating the t on the feasibility of application at the moment reinforcing material. The choices and the square application is available on the surface of the shaft sleeve or the shaft and sleeve at the same time is made for a particular connection with the proposed degree of hardening, the specific shear strength reinforcing materialand length (stage) partial fitting parts l, which is the ratio of (1).

The method is as follows.

Initially producing the process of partial pressing of the parts with the measurement efforts of crimp. Then, if the pressing force will take a given value, for example corresponding to condition (1)on the loose sections of the articulating surfaces of one or both parts (1 and 2, figure 1) cause a hardening material. After application of the material are finish pressing parts to the end position corresponding to the length of the connection l1.

In that case, if the pressing force does not take a value corresponding to the condition (1), throughout the process of pressing on the length l1then consider that the joint strength is sufficient, and hardening the material is not applied.

The coating material is produced in a known manner, which depends on the type (composition) of the material and the technology of its application. The material can be applied after stopping or without stopping the process of pressing, for example, in the automatic mode with the help of special devices for its application, and after removing the parts from the table and forging equipment.

An example of performing the method.

Implemented the proposed method for the Assembly of the sleeve of steel 40X with a bore diameter D=32 mm and an outer diameter of D1=60 mm and a wall of bronze Brag. Coupling length l1=40 mm. Acting on the connection maximum operating shear axial load Te=34 kN, Te·n=38 kN.

To implement the method were made twenty samples of compounds with an interference fit in which the values of the tightness was changed in the range from 20 μm to 65 μm, which can reasonably be considered relevant landing

(Nmin=23 ám, Nmax=64 μm). As a hardening material applied anaerobic material Anyterm 6 (EN-6) with.

The pressing of the compounds was carried out at a low speed on universal testing machine, CDMA-30 recording efforts chocking on a chart paper on which have been previously applied control borders and checkpoints in accordance with the illustration in figure 2. It was supposed application of anaerobic material only on the joined surface of the shaft.

When the value of the effort of pressing corresponded to the ratio of (1), was determined visually from graphs (figure 2)and also by comparing the value is of the efforts of the fitting with the control values at the points m=1...10. This more efficient use of the computer measurement system.

When the pressing force took a value corresponding to the condition (1), the process of partial embedding stopped, and the free surface of the shaft (1, 1) using the brush was applied anaerobic material. After application of the material compounds were dopasowywanie to the final position (length l1=40 mm) and was maintained for anaerobic polymerization of the material in the zone of contact details. Then the connection wypracowanie with the measurement of the initial effort of removing Tin. For all compounds was performed strength condition Tin>Te·n.

Implementation of the proposed method has shown that when the ratio of (1) only nine compounds from twenty have used the technology of hardening by applying anaerobic material, and for the four compounds in the moments when the shaft has already been pressed more than half of its length. When assembling the eleven compounds of the condition (1) is not performed on the entire process of pressing to the final position of the parts, therefore, anaerobic hardening material was not applied, and the strength of the connections was provided solely through the tightness. Finally, when implementing the method in a three times reduction in the consumption of hardening material (n is compared with the variant, when the material was applied would be the Assembly of all joints and the entire mating surface of the shaft and, accordingly, decreased costs associated with its application, i.e. confirmed the effectiveness of the proposed method.

Thus, when implementing the proposed method simplifies the process of Assembly of parts, and reduces the cost of hardening compounds, as reinforcing material is applied on the joined surface details only when necessary to achieve the specified strength of the connection.

The proposed method provides a technical effect and can be carried out using means known in the art.

Sources of information

1. Zamyatin VK Technology and equipment Assembly production maszynopisania: a Handbook. - M.: Mashinostroenie, 1995. - 608 S.: ill.

2. Balatsky LT Strength and forging connections. - Kyiv: Tekhnika, 1982. - 151 S.: ill.

3. USSR author's certificate No. 637229, CL VR 11/02, 1977.

4. Vojacek I.I. Application of anaerobic materials when assembling the fixed connection type shaft-bushing // Assembly in mechanical engineering, instrument-making. - M., 2003, No. 9. - Pp.33-37.

5. Machine parts / Vagorovskiy, Cieselski and others - M.: Mashinostroenie, 1972. - 504 S.: ill.

6. Ivanov M.N. The details of machines: Textbook. for students of technical colleges / edited Wainapanapa. - M.: Higher. HQ., 1998. - 383 S.: ill.

How is soedineniya parts with tension by pressing with the application of a hardening compound material, including partial pressing parts with measurement efforts pressing and then the finish pressing, characterized in that undertake partial pressing parts, then on free sites connected surfaces of one or both parts cause hardening compound material, followed by their subsequent finish pressing.



 

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