RU2262426C1 - Metal-polymer tube ultrasonic seam welding method - Google Patents

Abstract

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

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 motion direction of tubular blank and subjected to ultrasonic oscillations along its rotation axis; extruding polymeric material onto surface of welded tube. Welding is realized at roller rotation speed Vr exceeding speed Vt of tubular blank motion. Value Vr is selected in range Vr = (1.1 - 1.4)Vt. Pressing effort Fpr of roller to tubular blank is selected in range 4 - 8 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 well-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 rather 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 force of pressing 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 rotation speed V _p of the roller close to the speed V _{t of} moving the tubular billet ( V _p = V _t ).

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 with a speed V _{p of} rotation of the roller, close to the speed V _{t the} movement of the tubular workpiece, and a small amount of effort F _pr clamp it is not possible to eliminate this defect.

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 productivity of the MPT manufacturing process as a whole decreases.

The problem solved by the invention is to improve 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 increase productivity, 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 polymer material onto the surface of a welded pipe is performed at a speed V _{p of} rotation of the roller greater than the speed V _{t of} movement of the tubular workpiece, while the speed of rotation of the roller V _p is chosen within V _p = (1 , 1 ÷ 1.4) V _t , and provide a force F _{pr of} clamping the roller to the tubular billet in the range from 4 kg to 8 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 drawings.

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 slipping roller.

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 speed of rotation of the roller V _{p was} chosen to be greater than the speed V _{t of} movement of the tubular workpiece (V _p > V _t ). The experiments were carried out in the range from V _t = V _p to V _p = 1.5 V _p with efforts F _pr clamping the roller from 1 to 12 kg. An ultrasonic seam welding of MPT was performed from strips of aluminum or 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 _o (synchronous welding - to each one point of movement of the roller corresponds to one point of movement of the tubular workpiece) the resulting force F _Tr (shown in figure 1) does not arise due to the lack of slipping of the roller. At V _p > V _t , the effect of slipping of the roller relative to the tubular workpiece is realized, as a result of which additional sliding friction (F _Tr ) _ck occurs, i.e. the tangential component of external additional friction, which under certain modes of ultrasonic seam welding allows to obtain a high-quality weld. The difference in speeds V _p -V _t = V _ck - the speed of sliding (slipping). Thermal energy is released due to additional sliding friction. The welding time due to slipping of the roller does not change, and the appearance of additional heat due to additional external friction is due to the larger area S _{p of} rolling in the roller per unit area S _{t of the} workpiece (Fig. 1). S _p / S _t = V _p / V _t . (When V _p = V _t , respectively, S _p = S _t ).

Under the action of the pressing force F _{pr of the} roller clip from 1 to 12 kg, it is necessary to overcome the external sliding friction and advance the tubular workpiece (U-shaped metal strip with overlapping edges) at a speed V _c relative to the roller, if it did not rotate (model) V _c = V _p -V _t .

The best results for obtaining a high-quality weld for various materials and metal strips of different thicknesses were obtained at a speed V _{p of the} roller in the range of V _p = (1.1 ÷ 1.4) V _t and with a force F _{pr of} pressing the roller against the tubular workpiece in the range from 4 kg to 8 kg.

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

рез=

пр+

ск,

rez =

pr +

ck

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

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),

пр - сила трения от усилия F_пр прижима ролика,

pr - the frictional force from the force F _pr clip roller,

ск - дополнительная сила трения скольжения, возникающая от пробуксовывания ролика.

ck is the additional sliding friction force arising from the slipping of the roller.

Thus, at V _p = (1.1 ÷ 1.4) V _t and with a force F _{pr of} clamping the roller to the tubular billet in the range from 4 kg to 8 kg, the friction force increases with a fixed value of the clamping force in this interval. 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 is f = 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.

At a fixed welding time, an increase in V _p relative to V _p = V _t does not lead to an additional decrease in the welding time, however, heat is generated sufficiently to obtain high-quality welding.

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, due to the slipping effect, it is possible to reduce the height of the corrugations of the corrugated 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 billet and a small amount of pressing force F _pr, it is not possible to align the corrugations, since the roller goes around the corrugated surface (Fig. 4a), and poor weldability of the corrugation occurs. Under the indicated modes, due to the slipping effect and under conditions similar to thermo-ultrasonic welding, crushing, drawing and high-quality boiling of corrugations of an aluminum or copper strip of a tubular billet occurs (Fig.4b), which subsequently, after applying the polymer layer, leads to an increase in the quality of 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 _p > V _t . 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 _p > V _t leads to accelerated destruction of the oxide film, which further reduces the welding time and improves the quality of the weld without increasing the power of the generator of the ultrasonic vibrating system.

In addition, studies have shown that the use of the slipping effect of the roller 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 rate of the tubular workpiece, and 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 _p = 1,1, V _t = 4 m / min, F _CR = 4 kg, F gap = 850 N.

Example 2

It was carried out analogously to example 1.

When V _p = 1.25, V _t = 4 m / min, F _CR = 4 kg, F gap = 870 N.

Example 3

It was carried out analogously to example 1.

When V _p = 1.4, V _t = 4 m / min, F _CR = 4 kg, F gap = 950 N.

Example 4

When V _p = 1,1, V _t = 6 m / min, F _CR = 5.5 kg, F gap = 900 N.

Example 5

V _p = 1.25, V _t = 6 m / min, F _ol = 5.5 kg, F gap = 1040 N.

Example 6

V _p = 1.4, V _t = 6 m / min, F _ol = 5.5 kg, F gap = 980 N.

Example 7

V _p = 1,1, V _t = 8 m / min, F _CR = 8 kg, F gap = 910 N.

Example 8

V _p = 1.25, V _t = 8 m / min, F _CR = 8 kg, F gap = 920 N.

Example 9

V _p = 1.4, V _t = 8 m / min, F _CR = 8 kg, F gap = 830 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 the welding is carried out at a speed V _{p of} rotation of the roller, a greater speed V _{t of} movement of the tubular billet, while the speed V _{p of} rotation of the roller is chosen within V _p = (1,1 ÷ 1,4) V _t and provide a force F _pr clamping the roller to the tubular workpiece in the range from 4 to 8 kg

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