FI117982B - Metal belt manufacture for use in paper/board machine or in finishing machine, includes placing metal belt blanks narrower than final belt width side-by-side and/or in succession, and welding joints by friction welding - Google Patents

Abstract

Metal belt manufacture includes placing, side-by-side and/or in succession, metal belt blanks (10a, 10c) narrower than a final belt width in a number needed by a metal belt (102) of desired width and length, and welding joints by friction welding. The joints develop a composition similar to basic material of belt.

Description

, 117982

Method for manufacturing a metal belt for use in a paper / board machine or a post-processing machine

The present invention relates to a method of manufacturing a metal belt for use in a paper / board machine or a post-processing machine.

Endless steel belts are used, for example, in a metal belt calender and in a Con-deBelt belt dryer. Today, metal belts are made of metal belts manufactured by traditional melt-metallurgical processes and further processed by various hot and cold forming processes. Typically, the raw material for the strip is a stainless steel strip which is welded to form an endless strip. Next, the principle of making such tapes will only be outlined, as it will be readily apparent to one skilled in the art. According to Perin-15, the strip is manufactured by melting scrap metal and / or ore concentrate and the necessary alloying elements, for example in an electric furnace. The melt is then macerated in a converter to obtain the desired carbon content. After lamination, the steel is alloyed as desired prior to the ladle treatment. The melt is then cast into a blank which is transferred directly to hot rolling, where the blank is rolled under high temperature in a number of steps so that it becomes thinner and, of course, increases in width and length. At the end of the hot rolling, the rolled strip • · • · · is wound up and delivered for cold rolling. In a cold rolling mill • * * *; *. *. * Steel strip is first annealed to smooth the internal structure and etched * · * · ** '25 to clean the strip surface. Thereafter, the actual cold rolling begins, in which the steel strip is thinned cold to its final thickness. If necessary, ♦ · · the strip is annealed between the rolls if the degree of rolling is special • · * * * '. its great. Finally, the tape can be finished by sanding, annealing ..... and pickling. In addition, it can be lightly rolled to finish the surface • ·, · [30 and improve the flatness. After that, tape * *; **. webs of required length and width can be cut, the ends of which are welded together to form an endless metal belt, typically either by TIG welding or by laser. The width of the roll mills limits the width of the billet material to 1500 mm or 2000 mm, depending on the billet material, so that there is a large amount of welded 5 seams on the belt used at the widths of the paper machine. Metal belts are subjected to both fatigue loading and corrosion stress. Because of these factors, the belts need to be replaced from time to time due to the corrosion fatigue that occurs in them. In addition, the belts are subjected to strong abrasive forces, which should result in a sufficiently strong and surface-hard material. If the hardness is not sufficient, scratches may occur on the strap, which can cause fatigue cracking. The mechanical properties of the weld are typically about 20% lower than those of the base material, which can lead to seams being exposed due to wear or abrasion. A scratched or otherwise uneven belt, for example, consumes the seals of a strip dryer quickly and causes problems, for example. tel-15 for the disease.

The object of the present invention is to provide a method for improving the properties of the prior art belt.

In order to achieve this object, the method according to the invention is characterized in that the method comprises forming a metal belt by positioning it. a plurality of metal strip blanks narrower than the final width of the metal belt, adjacent and / or in succession to the desired width and length of the desired belt, and the seams between them are welded by a frictional joint in which the joint is substantially similar in composition.

• · · * · ·

The metal belt blanks may be formed, for example, to a length corresponding to the final width of the belt and be • located substantially * * relative to the longitudinal direction of the belt. perpendicularly, whereby all the weld seams are respectively substantially perpendicular to the longitudinal direction of the belt. The metal belt blanks can also be formed to a length corresponding to the final belt length and positioned adjacent to the final belt width, whereby the weld seams between the belt blanks extend substantially in the longitudinal direction of the belt. The ends of the metal belt blanks corresponding to the final length of the belts may be cut off at a non-rectangular angular position with respect to the longitudinal direction 5 of the blanks, the weld seam between the ends being correspondingly angular with respect to the belt length. The adjacent belt blanks are then preferably disposed such that their end seams are formed as a substantially continuous diagonal seam. The metal belt blanks can also be made into blanks 10, which are placed side by side and extend longer than the final width of the belt, with the longitudinal seams of the blanks extending obliquely to the longitudinal direction of the final belt. It is also conceivable to first make the belt wider than the final width and then to cut / grind it to its final width.

! 15 Friction Welding (FSW) uses a wear-resistant rotating tool that projects into the groove between the pieces to be joined and causes heat to be attached to the pieces to be joined by friction. In this case, the pieces soften without melting and the soft material is pushed from the front of the rotating tool to the rear of the rotary tool, which forms a weld. The weld seam has a composition similar to that of the base material. The seam provides substantially the same πει * ·]: mechanical properties as the base material by suitable heat treatment, which avoids the appearance of the seams due to wear or abrasion.

: Welding is performed against the anvil, whereby the underside of the seam is • exactly * the same as the base material and the belt does not need to be sanded to the outer surface. Also, FSW welding does not cause thermal breezing to get the belts. mittatarkoiksi.

* · * • · · * * * • t · »·» · •. For example, in a metal belt calender, the inside of the steel belt cycle is • • in direct contact with the supporting guide rollers. The outside of the belt loop may be • ·] ·] 30 in direct contact with the thermal roller, for example in case of web break * * *: **] in the absence of a transom between the contact surfaces. • · · • * 4 has been observed during trial runs; 1 1 7982 dipping scratches and wear on the inside of the belt. The belt outer side of termotelakontaktissa it has also been found for the current and scratching. In the roll contact of the belt a so-called "contact" is created between the belt and the pulley. grip area and glide area (Contact Mechanics, K.L Johnson, 1985).

5 On the inlet side of the contact, the strap goes straight into the grip area, but a slip area is created on the downstream side of the contact.

Two situations can be distinguished.

10 1. Belt Contact Cooling Belt (eg Cooling Roller)

When the belt comes into contact, it has a tensile strength σν. The strap goes straight into the holding area. As the belt cools, an increase in tension due to thermal tension (friction) occurs, since in the holding area the belt shrinkage and slip 15 are prevented by friction. Similarly, as the tension increases, the normal pressure exerted by the belt increases locally. As the belt advances to the downstream slip area, thermal stress is released through the slip. In this case, the tension induced in the holding region of the belt is restored to the level of tensile stress σν while the belt is shortened due to heat shrinkage.

In this case, the tensile stress is released as a skid in the forward direction (the belt slides in the opposite direction to the roll). The velocity of the • 25 nanowires exiting the contact is thus slightly slower than that of the incoming belt. . ·. speed.

30 mm The belt comes into contact with the tension tc and goes straight again * ·. »7: to the holding area. As the belt warms up, compressive thermal stress is generated • M • · 5 117982 #, which reduces tensile stress. If the temperature change is very large, the tensile strength in the holding area will be reduced to zero (stress free state) or even go to the compression side. This may cause the belt to buckle, i.e. the belt will come off the roll.

5

As the belt progresses, the belt tension will return to a level corresponding to the tensile stress σν. Leveling occurs via gliding, this time in the direction of travel. The velocity of the exiting belt is also slightly higher than that of the incoming belt.

10

As a massive thick-shell body, heat fluctuations are confined to the surface of the roll, so that no deformation of the roll occurs in the circumferential direction.

Instead, the belt as a thin material warms / cools thoroughly, and the heat deformation is more pronounced. The difference between the thermal expansions reali-15 plays as a slip.

It is also an object of the invention to provide a solution whereby the belt of a device using a metal belt of a paper / board machine or a post-processing machine does not undergo thermal stresses or deformations and can reduce or prevent belt scratching.

To achieve this goal, the metal belt of a metal belt calender or of a tensile belt processing machine using a metal belt is made of a material which: has a very low thermal expansion coefficient, preferably 2 x 10'6 • · • · 25 or less. The optimum situation is if the thermal expansion coefficient is set to zero. Such- I struck the belt in heating and cooling situations without heat stress and • · · • ♦ ·. · * ♦. thermal deformation. For these reasons, the resulting slip is not removed and the strap * · · does not scratch. One solution to the above requirement is a finished * ·. ··· back strap made of high-nickel Invar® steel with a thermal expansion coefficient of> 30x approx. 1 x 10 "6, which is less than 1/10 of the value of conventional steel. - * * • · elongations and thus slip are 1/10 of the equivalent of a normal belt.

♦ * · • · 6 117982

Any other alloy or alloy that fulfills other conditions, such as Inconel® or other high-nickel steel or stainless steel, may be selected as the belt material. The belt must have moderate thermal conductivity (at least 5-10 W / mK) and moderate specific heat capacity to act as a heat transfer medium. In addition, the belt must have good strength, workability, weldability and corrosion and fatigue resistance.

The cost of strap material is not a very important factor if the benefits are overwhelming. For example, the price of the raw material can be roughly 3-5 times 10, if the manufacture is made easier and cheaper, and above all if the length of the belt (belt replacement interval) is increased by several times.

The savings in production are significant if the belt does not need to be sanded at all, or if only the replacement interval (production interruptions) can be reduced to half.

The advantages of Invar® steel include:

- thermal expansion up to 1/10 of the value of normal steel, significantly reducing scratching • · • * · * 20 - fretting properties are remarkably good, · · ·: V - good workability • · · is very weldable when welding no thermal stress and no tension * »·; *: φ: - sufficient thermal conductivity, though slightly lower than normal • · * *: lf crackers.

25th . ·, One possibility is to manufacture the belt in whole or in part in a powder metalluric »» · • · ·. * ··. cally. Thanks to powder technology, the Strap material is • * * smoother, denser, cleaner and has a finer microstructure • «, ···, more subdivided for traditional wear and corrosion resistance • ♦ * · ψ 30 substantially better than manufactured belts. Therefore, • · • · V '. • the belt change interval can be much longer than conventional belts and therefore • · 7 117982 reduced production and belt replacement costs. By using powdered parts, the free maintenance interval can be increased by 3 to 8 times that of conventional components. A further advantage is that it is also possible to make powder blends which are difficult or practically impossible to produce by conventional means. Powder metallurgy makes it possible to make stainless steel belts with the same corrosion resistance as titanium and high-nickel alloyed so-called super-steels, but at a much lower price than these, and for example to make stainless steel belts which have the same corrosion resistance as so-called super-steels with titanium and high-nickel alloys, but at significantly lower prices.

Some embodiments of the metal belt according to the invention will now be described with reference to the accompanying drawings, in which:

Figures 1a to la schematically illustrate some ways in which the metal belt blanks used to make the metal belt.

Fig. 2 schematically shows an application of a metal belt calender, and «·«%% • * * t * * *. . ·. Figure 3 shows a metal belt calender equipped with a threading device.

Fig. 1a schematically illustrates a metal belt 102 formed by metal belt blanks 10a, the length of which corresponds to the final width of the metal belt 102. The metal belt preforms 10a are disposed side by side and welded to each other by friction welding, whereby weld seams 11a are formed between them. 30 are substantially perpendicular to the longitudinal direction of the metal belt.

«· ·

Figure Ib illustrates the formation of metal strap 102 from metal strip blanks 10b substantially corresponding to the final length of the metal strap 117982, whereby the seam 11b between the blanks is formed substantially in the longitudinal direction of the metal strap. The seam between the opposing longitudinal ends of each metal belt 10b may be substantially perpendicular to the longitudinal direction of the metal belt 5, with the ends of adjacent metal belt blanks 10b disposed substantially aligned in the width direction of the metal belt 102 to form a substantially perpendicular the opposite ends of the blanks 10b are cut in an oblique position with respect to the longitudinal direction of the blank 10 and adjacent blanks 10b are disposed relative to one another to form a substantially uniform seam extending diagonally across the metal belt 102, denoted by reference numeral 12a. Fig. 1c shows another alternative embodiment in which the metal belt blanks 10c are disposed adjacent to each other in the oblique position relative to the longitudinal direction of the final metal belt 102, whereby the seams 11c therebetween also extend in an oblique position relative to the longitudinal direction of the ribbon 102. The longitudinal ends of the blanks 10c are incised to substantially correspond to the longitudinal edge of the final strip 102. Various combinations of the above belt manufacturing methods are also possible, e.g., positioning several metal belt blanks • 1 · 1 shorter than the final length of the metal belt to obtain a length corresponding to the final belt length, and • adjacent to the final belt width required. amount. The metal • 7 V Strap can also be thought of as having a final width of sheet * * 1 • · · .1 ··. * · • 1 · 25 to its full width after welding the strip.

• · · • · ·

When using a conventional metal belt, for example a stainless steel belt, a temperature difference is formed in the metal belt calender between the metal belt and the thermal roller, resulting in belt wear.

• · · 30 • 1 * «1 · • ♦ · • 1 · * 1 9 117982

ι * I

To prevent the temperature difference between the metal belt and the roll, for example, the heating hood solution of Figure 1 may be used. In Figure 1, the metal belt 102 wraps around the heated guide rollers 103. The heating coil is formed by a warm 100 placed on one side 5 of the belt 102 and a mirror 101 placed on the other side. Alternatively, a heater may be provided on each side of the belt. The mirror and heater may also be disposed opposite to that of FIG. 1, i.e., the mirror may be located outside the belt loop and the heater may be located inside it. The heater may operate, for example, on hot oil, gas, electricity, water, steam or induction. In Figure 1, reference numeral 107 denotes a heat source, e.g., a hot oil system from which heat is supplied to heater 100. To minimize convection of belt 102, the gap between belt and hood 100, 101 should be minimized. Figure 1 also shows an optional auxiliary heater 105 for controlling the temperature of the belt in the contact area of the guide roller 103 of the belt 102 and 15.

Fig. 2 schematically illustrates a threading device 110 suitable for use with a metal belt calender, utilizing a calender metal belt 102. The belt 102 passes around the guide rollers 103 and forms a processing zone between them with a thermal roller 104 which serves as a counter element. The PN through which the web to be processed is passed. The belt 102 is preferably manufactured in accordance with the invention by welding the seams of the belt by friction welding.

• · * • · ·

The web W passes in a normal rotation with the metal strap 103 • · · • · ·

. ···. 2 counterclockwise in the example of FIG. 2, and then the PN of the treatment zone

• · · 25 and around the thermal roller 104 for further processing. When handling the same calendering: buffer both sides of the web of the web can take Wi broken lines in Figure 2 ·· * [** I of the processing path directly between the metal belt and the thermo roll ·: ··· zone of processing the second half of a PN the web to the calendar requires two threading device 110. The web Wi is directed to the processing zone ·· *. ···. After 30 PN, around the guide roller 108b for further processing.

The threading device 110 is arranged to run, e.g., along a conductor 112 in the form of a C-beam following a metal belt rotation 102. The device has an actuator which presses against the metal belt 102 of the web W and starts to move with the belt either by friction or by a drive motor, whereby the threading device 110 5 passes along the guide 112 to receive the actuator force. The air supply can be tracked, for example, by means of a ball closure arrangement known from the suction tables or by other air barrier arrangements of piston rodless cylinders. The actuator may also be electrically operated, whereby the load is controlled by a spring relative to the position and the electrical energy is transmitted by the coals. The drive motor drives the device at the desired speed. The device is designed to be as light as possible to ensure good initial acceleration. The acceleration can be achieved, for example, by means of a pneumatic cylinder 111 or by means of a tuned spring.

• · • 1 2 • · · • 1 · • «• 1 • 1 1 • 1 * · 1 · #: '·' · # 1 ····. · * 1 · * ♦ · • · 1 * 1 · • · 1 »• · 4 * · • · ♦ 1 1 • · · • 1 · • 1 · • ft 1 • · • · • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Add · ·· 1 • · 1 • · ♦ • ft1 ft 2 ft.

• «1 • ft y

Claims (6)

Method for producing a metal strip (102) used in a paper / cardboard or finishing machine, characterized in that in the process the metal strip is formed by placing more metal strip blanks (10a; 10b; 10c) closer than the final width of the metal strip. one another and / or one after the other in a number required by the desired width and length of the strip (102) and their intermediate joints are welded with friction welding, where the joint is formed in a substantially similar composition, as the base blank. The method according to claim 1, characterized in that the metal strip (102) is heat treated to substantially remove the voltage differences between the joints and the base blank. 15 The method according to claim 1 or 2, characterized in that metal strip blanks (10a) are formed in the corresponding width of the strip (102) and placed perpendicularly to the longitudinal direction of the strip, the weld joints (11a) of the adjacent blanks being substantially similar. perpendicular: 1 2 3 ··· 20 relative to the longitudinal direction of the belt. • · · • 1 1 • · • · t The method according to claim 1 or 2, characterized in that the metal strips (10b) are formed in a final length of the strip (102) corresponding to a length of 1 and placed next to each other corresponding to the final width of the strip, wherein the weld joints (11b) between adjacent blanks extend substantially in the longitudinal direction of the belt. ··· • · · * 1 · • · * · • · · 't. The method according to claim 1 or 2, characterized in that metal strips (10c) are formed at a length greater than the final width of the strip (102) and placed next to each other in a relative relationship. longitudinal direction of the belt * 1 · • · · • 1 2 · 1 · 3 • oblique position, whereby the weld joints (11c) between the blanks in a corresponding manner have an oblique position in relation to the longitudinal direction of the belt. The method according to any one of the preceding claims, characterized in that the band material is selected from the group consisting of: high nickel base, e.g. Invar® or Inconel®, stainless steel or powder metal. ·· • ·· • ♦ · · · · · · · · ··· · · · · · · · · · ♦ ♦ ♦ · · · · · ♦ 1 • · · · · · · · · · · · · · · ··· # • # ♦ ♦ · · · 1 • · # ♦ ♦ ♦ • · · · ♦ · ♦ · • ·