RU2262427C1 - Metal-polymer tube ultrasonic seam welding method - Google Patents

Abstract

FIELD: metallurgy, namely tube manufacture by ultrasonic welding, for example making metal-polymer tubes.

SUBSTANCE: method comprises steps of forming continuous metal strip to U-shaped profile blank; twisting U-shaped profile blank to tubular one with overlapping edges at moving tubular blank along its lengthwise axis; welding overlapped edges of tubular blank by means of roller rotating in direction of tubular blank motion and subjected to ultrasonic oscillations along its rotation axis; extruding polymeric material onto surface of welded tube. Welding is realized at motion speed Vt of tubular blank exceeding speed Vr of roller rotation. Value Vt is selected in range Vt =(1.05 - 2.0)Vr; pressing effort Fpr of roller to tubular blank is provided in range 3 - 6 kg.

EFFECT: enhanced quality and operational characteristics of metal-polymer tubes.

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Description

The invention relates to a technology for manufacturing pipes by ultrasonic welding and can be used in the manufacture of metal-polymer pipes (MPT).

A known method of ultrasonic seam welding of a metal-polymer pipe, including forming a workpiece from a continuous strip of metal into a U-shaped profile, rolling up a strip of metal into a tubular workpiece with overlapping edges when moving the tubular workpiece in a direction along its longitudinal axis, welding the overlapping edges of the tubular workpiece with a roller rotating in the direction of movement of the tubular billet and performing ultrasonic vibrations along its axis of rotation, extrusion of the polymer material on the surface arena pipes (Patent of the Russian Federation No. 2126322, B 29 C 47/02, publ. 1999).

This known method is implemented in the installation for the formation of MPT No. LT 002, manufactured by CJSC Mayak-93 Scientific-Production Enterprise since 1998. The advantage of the method is the relatively high productivity of MPT manufacturing due to the continuity of the manufacturing process of the product in a single technological cycle. The limitation of the method is the insufficiently high quality of the MPT, caused primarily by the small pressure of the roller against the tubular billet (the force F _{pr of} pressing the roller against the tubular billet was up to 3 kg) and the choice of the speed of rotation of the roller V _p close to the speed V _{t of} moving the tubular billet.

In addition, when forming the tubular preform itself from a continuous strip of metal by means of a forming device (die or several dies) in the area of overlapping edges, surface corrugation always occurs, which is directly related to the bending of the edges of the metal strip. When welding at a speed V _{p of} rotation of the roller close to the speed V _{t of} movement of the tubular workpiece and a small amount of force F _pr clamp it is not possible to eliminate this defect and to obtain a high-quality seam.

The closest is the method of ultrasonic seam welding of a metal-polymer pipe, which includes forming a workpiece from a continuous metal strip into a U-shaped profile, folding a metal strip with a U-shaped profile into a tubular workpiece with overlapping edges when moving the tubular workpiece in the direction along its longitudinal axis, welding of overlapping the edges of the tubular workpiece by a roller rotating in the direction of movement of the tubular workpiece and performing ultrasonic vibrations along its axis of rotation, extrusion of polymeric material is on the surface of the welded pipe (Patent of Russian Federation №2076784, B 21 C 37/08, publ. 1989 YG).

This method is described in a patented device. In this technical solution, the ultrasonic welding roller is equipped with a drive that allows the rotation of the roller with a speed V _p equal to the speed V _{t of} movement of the pipe.

The limitations of this method are all the above disadvantages. In addition, due to the need to synchronize the rotation drives of the roller with the movement of the tubular workpiece, the welding time increases, which reduces the productivity of the MPT manufacturing process as a whole.

The problem solved by the invention is to increase productivity, as well as improving the quality and technical and operational characteristics of manufactured metal-polymer pipes.

The technical result that can be obtained by implementing the method is to reduce welding time, improve the quality of MPT.

To solve the problem with the achievement of the specified technical result in the known method of ultrasonic seam welding of a metal-polymer pipe, which includes forming a workpiece from a continuous strip of metal into a U-shaped profile, folding the strip of metal with a U-shaped profile into a tubular workpiece with overlapping edges when moving the tubular workpiece in direction along its longitudinal axis, welding of the overlapping edges of the tubular workpiece with a roller rotating in the direction of movement of the tubular workpiece and owl According to the invention, welding ultrasonic vibrations along its axis of rotation, extrusion of a polymeric material onto the surface of a welded pipe is performed at a speed V _{t of} moving the tubular workpiece greater than a speed V _{p of} rotation of the roller, while the speed V _{t of} moving the tubular workpiece is selected within V _t = ( 1.05 ÷ 2) V _p and provide the force F _pr clamping the roller to the tubular workpiece in the range from 3 to 6 kg

These advantages, as well as features of the present invention are illustrated by the best option for its implementation with reference to the accompanying figures.

Figure 1 depicts a model implementation of the method, a view from the side of the longitudinal axis of the welding roller;

Figure 2 is the same as figure 1, a view from the side of the transverse axis of the welding roller;

Figure 3 - physical model of ultrasonic welding with slippage of the tubular workpiece;

Figure 4 - without welding: a) a model of processing the corrugated surface of a tubular workpiece in accordance with analogues, b) a model of processing a corrugated surface of a tubular workpiece in accordance with the claimed method.

In accordance with the claimed method (FIGS. 1, 2) _{, the} movement speed V _{t of} the tubular billet was selected at a higher roller rotation speed V _p (V _t > V _p ). The experiments were carried out in the range from V _t = V _p to V _t = 2.5 V _p with efforts F _pr clamping the roller from 1 to 10 kg. An ultrasonic seam welding of MPT was performed from strips of aluminum and copper metal with a thickness of 0.18 ÷ 0.5 mm at a frequency f of ultrasonic vibrations of 22000 Hz.

In accordance with analogues V _t = V _p = V ₀ (synchronous welding - to each one point of movement of the roller there corresponds one point of movement of the tubular workpiece) and the force (F _Tr ) _ck (shown in Fig. 1) does not arise due to the absence of tubular slippage blanks. At V _t > V _p , the effect of slipping of the tubular workpiece relative to the roller is realized, resulting in additional sliding friction, i.e. the tangential component of external additional friction, which under certain modes of ultrasonic seam welding allows you to get a high-quality welding seam. The speed difference V _t -V _p = V _ck is the speed of sliding (slippage).

It is clear that when the tubular workpiece slips, the welding time decreases (the roller is in the welding area less time), therefore, in the experiment, the power of the ultrasonic generator and magnetostrictor was chosen with a margin. Under the action of the pressing force F _{pr of the} roller clip from 1 to 10 kg, it is necessary to overcome the external sliding friction and advance the tubular workpiece (U-shaped metal tape with overlapping edges) at a speed V _c relative to the roller, if it did not rotate (model).

It may also be necessary to reduce the roller pressing force F _pr to obtain high-quality welding.

In Experiment V _t = 2,5V _p been limited mainly limit power setting. Best results suture receiving quality for different materials and different thickness metal bands were obtained at a speed of movement V _t of the tubular blank within V _{m = (1,05 ÷ 2,0) V p} , and _{so forth} with a force F pressing the roller to the tubular workpiece in the range of 3 to 6 kg.

Figure 3 shows the physical model of welding in accordance with the claimed method.

рез=

np+

ск, где

rez =

np +

ck where

рез - результирующая сила трения, полученная по правилу векторного сложения (на фиг.3 она также показана пунктирным вектором, полученным параллельным переносом),

res - the resulting friction force obtained by the rule of vector addition (in Fig. 3 it is also shown by the dotted vector obtained by parallel transfer),

np - сила трения от усилия F_пр прижима ролика,

np is the frictional force from the force F _pr clip roller,

ск - дополнительная сила трения скольжения, возникающая от проскальзывания трубчатой заготовки.

ck is the additional sliding friction force arising from the slip of the tubular workpiece.

Thus, with V _t = (1.05 ÷ 2.0) V _p , and with a force F _{pr of} pressing the roller against the tubular workpiece in the range from 3 to 6 kg, the friction force increases and, therefore, the welding efficiency increases. As studies have shown, when going beyond the specified operating parameters, the welding quality does not improve. Specialists understand that ultrasonic seam welding (a type of friction welding) leads to heat loss and requires a power reserve of the ultrasonic generator.

When welding, it is necessary to expend a certain power or perform a certain work A ₀ , A ₀ = Ftr × S, where S is the path determined by the ultrasonic wave (Fig. 3), depending on the amplitude A and frequency f of ultrasonic vibrations, i.e. S = Φ (A; f).

, где W - мощность, t - время сварки.Since the frequency f = 22000 Hz = const, an alternative to increasing "Ftr" is to increase the amplitude of "A", i.e. paths "S" since

where W is the power, t is the welding time.

With a fixed welding time, a slight increase in V _t relative to V _t = V _p , for example, to V _t = 2.0 V _p leads to an additional decrease in the welding time.

In the case of V _t = V _p at a given power required for high-quality welding, you can compensate for the decrease in welding time either by increasing F _Tr or increasing the amplitude A of ultrasonic vibrations. However, an increase in F _Tr leads to significant losses of thermal energy, and in some cases can lead to jamming of the roller. An increase in the amplitude A of ultrasonic vibrations leads to an increase in losses by a factor of ² and to a reduction in the service life of the waveguide with the roller, and an additional power reserve of the generator with a magnetostrictor is required, which leads to some energy losses.

In the case of V _t > V _{p, the} quality of welding is ensured by a certain (Ftr) _cut without increasing the clamping force. An insignificant limitation of the claimed method in relation to analogues, if used under the indicated modes, is some wear of the roller and a slight increase in energy consumption.

At the same time, the use of friction force during ultrasonic welding under the indicated conditions allows the implementation of the so-called thermo-ultrasonic welding technology without supplying additional heat to the working tool — the roller. As shown above, thermal contact heating is carried out in the inventive method through the use of additional friction in combination with the action of ultrasonic vibrations.

In addition, through the use of additional friction, it is possible to reduce the corrugation of the surface of the tubular workpiece, which is directly related to the bending of the edges of the metal strip (Fig. 4a). When welding at a speed V _{p of} rotation of the roller, close to the speed V _{t of} movement of the tubular workpiece, and a small amount of force F _pr clamp it is not possible to align the corrugations and get a high-quality seam, since the roller goes around the corrugated surface (figa). In the indicated modes, due to the slippage effect of the tubular workpiece and in conditions similar to thermo-ultrasonic welding, the corrugation of aluminum or copper strip of the tubular workpiece is crushed, drawn and qualitatively boiled (Fig. 4b), which subsequently, after applying the polymer layer, leads to an increase in quality MPT.

The difference in the speeds of the roller and the tubular workpiece causes additional friction, independent of the parameters of the oscillating system and associated only with the kinematics of movement of the workpiece by selecting the appropriate drive parameters V _t > V _p . When using a workpiece made of a strip of aluminum metal, an oxide film (Al ₂ O ₃ , Al ₃ O ₄ ) is always present on its surface. Additional friction at V _t > V _p leads to accelerated destruction of the oxide film, which further reduces the welding time and improves the quality of the weld.

In addition, studies have shown that the use of the slip effect of the tubular billet allows a wider range to vary the magnitude of the pressing force and the amplitude of the ultrasonic vibrations of the waveguide (roller) than it was at V _t = V _p , and also allows you to increase the feed speed of the tubular billet therefore, to increase the productivity of manufacturing MPT without increasing the power of the generator of the ultrasonic oscillatory system.

Examples of specific implementation of the method.

Example 1

Tests were carried out on samples 25 mm long with a tubular billet thickness of 0.2 mm at break (F allowable gap = 700 N).

When V _t = 4 m / min, V _p = 3.8 m / min, F _CR = 3 kg, F gap = 720 N.

Example 2. V _t = (1.05 ÷ 2.0) V _p

It was carried out analogously to example 1.

When V _t = 4 m / min, V _p = 2.7 m / min, F _CR = 3 kg, F gap = 760 N.

Example 3

It was carried out analogously to example 1.

When V _t = 4 m / min, V _p = 2.0 m / min, F _CR = 3 kg, F gap = 800 N.

Example 4

When V _t = 6 m / min, V _p = 5.7 m / min, F _CR = 4.5 kg, F gap = 790 N.

Example 5

When V _t = 6 m / min, V _p = 4.0 m / min, F _CR = 4.5 kg, F gap = 810 N.

Example 6

When V _t = 6 m / min, V _p = 3.0 m / min, F _CR = 4.5 kg, F gap = 870 N.

Example 7

When V _t = 8 m / min, V _p = 7.6 m / min, F _CR = 6 kg, F gap = 710 N.

Example 8

When V _t = 8 m / min, V _p = 5.3 m / min, F _CR = 6 kg, F gap = 790 N.

Example 9

When V _t = 8 m / min, V _p = 4.0 m / min, F _CR = 6 kg, F gap = 820 N.

When going beyond the modes indicated in examples 1-9, the technical result is not achieved.

The most successfully claimed method of ultrasonic seam welding of a metal-polymer pipe is industrially applicable in mechanical engineering for the manufacture of a wide range of high-quality pipes.

Claims (1)

A method of ultrasonic seam welding of a metal-polymer pipe, including forming a workpiece from a continuous strip of metal into a U-shaped profile, rolling up a strip with a U-shaped profile into a tubular workpiece with overlapping edges when moving the tubular workpiece in the direction along its longitudinal axis, welding the overlapping edges of the tubular workpiece with a roller rotating in the direction of movement of the tubular billet and performing ultrasonic vibrations along its axis of rotation, extrusion of the polymer material on the surface l welded pipe, characterized in that welding is performed at a speed V _{t of} movement of the tubular billet, a greater speed V _{p of} rotation of the roller, while the speed V _{t of} movement of the tubular billet is selected within V _t = (1.05 ÷ 2.0) V _p and provide a force F _pr clamping the roller to the tubular workpiece in the range from 3 to 6 kg

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