SU1300210A1 - Threaded joint with indication of axial force of tightening - Google Patents

Abstract

The invention relates to the field of mechanical engineering and can be used in critical threaded joints requiring the provision of a calculated tightening force. The purpose of the invention is to reuse the indicator element. When tightening the threaded joint, the rod 3 is elongated, its sections 5, 6, and the cylindrical bore 7. During the tightening process, the indicator screw cannot get into the threaded section 5 due to the violation of the screw thread unification. When the required axial force is reached, the indicator screw can be screwed into both threaded sections. This means that the threaded connection has reached the specified tightening force. 1 3.p. f-ly, 2 ill. (Oh Fi. 1

Description

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The invention relates to mechanical engineering and can be used in critical threaded joints, which require a calculated tightening force.

The purpose of the invention is to reuse the indicator element.

Figure 1 shows the threaded connection, cross section; Fig, 2 - the same, with a threaded section at the inlet of the axial hole in the form of a sleeve, a cross section.

The threaded connection comprises a nut 1, a bolt 2 with a threaded rod 3, in which a blind axial bore 4 is made with a threaded section 5 near the blind end of the opening 4 and a threaded section 6 at the inlet part of the opening 4. The threaded sections 5 and 6 are separated by a cylindrical bore 7 that exceeds along the length of the threaded sections 5 and 6 and which do not interfere with the passage of the indicator screw (in Fig. 1, the indicator screw is shown in dotted lines, and not shown in Fig. 2, since its design can be any provided that it is made with the same thread and teaching heel 5 and 6). The bolt is placed in parts 8 and 9, FIG. 2 shows a variant of the design comprising a sleeve 10 with a rezbovy section 6, which is mounted on the inlet part 11 of the opening 4. The sleeve 10 can be fixed by any known method (on the thread, on the press fit etc.).

When the threaded connection is tightened, the rod 3 and its sections 5 and 6 and the cylindrical bore 7 are elongated, and the drilling 7 is basically lengthened. During the tightening process, the indicator screw cannot be screwed through the threaded section 6 into the threaded section 5, since - bore 7 leads to a violation of a single screw thread of these sections. Sections 5 and 6 are separated from each other, and the indicator screw does not fit into the thread of section 5. The preliminary calibration determines the change in the distance between sections 5 and 6, corresponding to the achievement of the required axial force, the thread angle is equal to this elongation. Then, when the required axial force is reached, the indicator screw can again be screwed into the threaded section 6, as well as into section 5, then

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ka is terminated. The indicator screw is removed from the rod 3.

Thus, for a threaded joint, designed for operation with an axial force of 20 tf (0.2 MN), the elongation of sections 5 and 6 and the bore 7 from the tensile force is determined by preliminary calibration. If a given force corresponds to an elongation that is not equal to the pitch of standard threads (for example, 0.35 mm), the axial size or diameter of the cylindrical bore 7 (or the depth of the hole 4) can be increased, which leads to an increase in elongation. The final design of the bolt is such that the elongation of the bore 7 is exactly equal to the thread pitch of sections 5 and 6 (for example, a standard thread pitch of 0.5 mm). When assembling such a threaded joint, the ability to screw the indicator screw into both threaded sections 5 and 6 means that an elongation equal to the pitch (i.e. 0.5 mm) has been achieved, which corresponds to the specified tensile force (20 tf).

The embodiment of FIG. 2 makes it possible to simplify the adjustment of the ratio of the thread pitch and the elongation of the cylindrical bore 7 of the axial bore 4 by fixing the bushing 10 in the axial bore at a desired distance from the threaded portion 5. This can be achieved, for example, by turning the support part 12 collar 13 of the sleeve 10. The twisting of the rod under the action of the torque applied to the nut can also be taken into account (this factor is absent when assembling by means of pre-stretching of the rod 3).

Claims (1)

1. A threaded connection with an indication of an axial tightening force, comprising a bolt with a blind axial hole and an indicator element placed in said hole, characterized in that, for the purpose of repeated use of the indicator element, the axial hole is filled with a cylindrical bore in the middle and threaded sections, the thread pitch of which is equal to the elongation of the cylindrical bore corresponding to the specified axial pulling force, and the indicator element It is made in the form of a screw with a similar thread, the length of which is not less than the depth of the axial bore. 2; Compound according to claim 1, characterized in that the threaded The section at the entrance of the axial hole is made in the form of a sleeve mounted in a bolt with the possibility of changing its position relative to the second threaded section. Editor M.Petrova Compiled by S. Nikulin Tehred M. Khodanych Order 1134/35 Edition 760 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. 2 Proofreader S. Shekmar