RU2343060C2 - Method of threaded joints welding - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: mated parts are preliminarily tightened by torque spanner with torque fixation. Period of thread tightening is determined with optimal torque at minimum value of misalignment, which is assessed by values of radial divergence of mated parts. Afterwards final thread tightening is done until optimal torque value is obtained. Then intermediate fixation is done at the butt end of threaded joint by means of tack welding. In order to do this, section is defined, which corresponds to maximum radial divergence on controlled surface in relation to base surface of joint parts. The first tack weld is made on diametrically opposite section. Mutual position of mated parts is measured, and sections for another two tack welds are identified in the same manner, then tack welds are made, and welding is performed along joint perimeter.

EFFECT: high accuracy of mutual position of two mated parts without toughening of technology for manufacture of separate product parts.

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Description

The invention relates to the field of engineering and can be used in the assembly for welding of threaded joints, for example, the body and nipple of a drill diamond bit; includes two stages - assembly of a threaded joint and perimeter welding.

A known method of assembling threaded joints [1], including pre-tightening, which is carried out with the influence of forced vibrations on the threaded connection, converting mechanical vibrations into an electrical signal, registering the quality parameter of the connection and final tightening with quality control of the obtained threaded connection to achieve the reference value of the quality parameter ( M _cells = const).

The disadvantage of this method is the unaccounted for factor of spatial deviations in the form of misalignment of two parts connected by a threaded connection, which significantly affects the operational performance of the product.

Also known is a method of assembling a gas burner [2], which includes a housing rotating in a sleeve that is mounted directly on the rear nipple of the burner outlet via a connecting nut. Its dimensions are so small that the diameter of the housing is less than or equal to the diameter of the thread of the nut. Thanks to this connection, a smooth power supply is not accompanied by turbulence, and since friction during rotation is very weak, the user practically does not feel sharpness when feeding.

The disadvantage of this method is that the structural diagram of the location of the tacks is not defined, and also the relationship of the location of the tacks with the accuracy of the relative position of the mating parts is not determined.

The technical result of the invention is to increase the geometric accuracy of two welded parts assembled by means of a threaded connection.

The technical result is achieved by pre-tightening the mating parts with a torque wrench with fixing the torque and determining the tightening period of the thread with the optimum torque at a minimum misalignment, which is estimated from the radial deviation of the mating parts, after which the final thread is tightened to the optimum torque moment, then intermediate fixation is carried out at the end of the threaded connection by performing tacks, d To do this, determine the area corresponding to the maximum radial deviation on the controlled surface relative to the base surface of the connection parts, and on the diametrically opposite section, the first tack is measured, the relative position of the mating parts is measured and the sections for two more tacks are similarly determined and tacks are performed, after which welding is performed perimeter connection.

When assembling the diamond bit, the body 2 and the nipple 3 are pre-oriented with a metric thread (see Figure 1). When tightening the threads, the ends of the nipple and the body are deformed. As a result of elastoplastic deformation, a change in the component size A2 of the angular dimensional chain occurs. A change in this component link leads to a change in the closing link of the dimension chain A, the value of which is measured by the misalignment parameter A _{Δ of the} axes of the housing 1 and nipple 4. To determine the permissible deformations of the threaded connection, which lead to the minimum misalignment A _Δ , the preliminary tightening is performed with a torque wrench with fixing torque. The preliminary tightening is carried out sequentially with increasing torque and at the end of each stage, the radial runout S _{i is} measured, where i is the reference number along the perimeter of the connection (see Figure 2).

where n is the index, which means the number of measurements of the radial deviation of the axes of the mating parts for a full revolution of the symmetrical connection with the selected sampling step.

The torque on the torque wrench M _cl with preliminary tightening of the thread is increased sequentially until the value of the radial runout begins to increase at the next stage j with respect to the previous j-1. The end of the preliminary assembly phase of the threaded connection is expressed by the following inequality

where j is the state number of the threaded connection at the time of its preliminary assembly.

Example. The table below shows the numerical values of the radial runout of the compound depending on the change in torque on the torque wrench (M _cells ):

j M _cells , N * m S _i , mm one 10 0.13 2 twenty 0.11 3 thirty 0.11 four 40 0.10 5 fifty 0.09 6 60 0.11

After the preliminary stage, the final assembly of the threaded joint is carried out, which includes the procedure of loosening and final tightening with the optimum torque (M _cells ) _j-1 . The quality of the final assembly of the threaded connection is checked by the value of the control measurement of the radial deviation of the mating parts, the value of which should be minimal when the threaded connection is finally assembled and satisfy condition (2).

The misalignment of the two parts to be connected is defined as a radial runout using a special measuring device (see Figure 2.). The installation consists of a plate and a magnetic stand with a dial indicator (indicator division value is 0.01 mm). In the plate there is a hole of high accuracy with a quality of H6, into which a diamond bit nipple is installed. The case is screwed onto the nipple and, using a magnetic stand with a dial indicator, the deviation from the center of the bore hole is measured for a full revolution of the connection. According to the measurement results mark the area with a polar angle φ in degrees, having the maximum value of the radial deviation of the location of the parts in the product.

At the next stage, the pre-fixation of the threaded connection is performed, performing the first tack at the end of the connection so as not to increase the amount of misalignment achieved during the final assembly of the thread. For this, it is necessary to determine the optimal coordinates of the tacks, which are a condition for a stable increase in the accuracy of the relative position of the parts to be joined at the welding stage.

The stage of determining the sector of the polar angle φ, the radial deviation of which has the largest value max S (φ) ∈i. Next, they carry out a tack of the body with the nipple in a place diametrically opposite to the sector with a maximum radial runout value of a certain value of the polar angle φ + 180 °. At the specified location, the first tack is performed, which leads to a change in the accuracy of the relative position of the connection (see Figure 3, a).

After the first tack, the relative position of the mating parts is measured again and a place is found for the second tack (see Figure 3, b). This process is repeated for the third tack (see Figure 3, c). After performing three tacks, the body is welded with a nipple around the entire perimeter of the bit.

In figure 1. diamond drill bit shown.

Figure 2. The installation for measuring radial runout (misalignment A _Δ ) of the diamond bit body relative to the nipple is presented.

Figure 3 shows a structural diagram of a change in radial runout after performing tacks and welding of the body and nipple.

Assembly for welding bits of the proposed method provides a several-fold increase in the accuracy of the relative positioning of the body and nipple (see Figure 3, d).

The proposed method of assembly for welding diamond bits allows for high accuracy of the relative positioning of the two parts to be connected without tightening the manufacturing technology of individual parts of the product.

List of sources

1. Patent R.F. No. 2277041, IPC V25V 21/00. Assembly method of threaded connections / Shuvaev V.G., Shtrikov B.L., Shuvaev I.V. Publ. in BI No. 15 dated 05/27/2006

2. FR 2607218, F16L 27/08. Demande de brevet d'invention. / Jean-Marie Tandart, Jean Louis Besset. 05/27/1988

Claims (1)

A method of welding threaded joints, characterized in that they pre-tighten the mating parts with a torque wrench and fix the torque and determine the tightening period of the thread with the optimum torque at a minimum misalignment, which is estimated from the radial deviation of the mating parts, after which the thread is finally tightened to the optimal value of the torque, then perform an intermediate fixation at the end of the threaded connection by performing at fleece, for which they determine the area corresponding to the maximum radial deviation on the controlled surface relative to the base surface of the connection parts, and on the diametrically opposite section, perform the first tack, measure the relative position of the mating parts and similarly determine the sections for two more tacks, and perform tacks, after which carry out welding around the perimeter of the connection.

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