DE19617717A1 - Process for continuously burning ceramic pipes and furnace for carrying out this process - Google Patents

Abstract

In the process for the continuous firing of ceramic pipes (30), the pipes (30) lie on two support bars (34, 35) running in the longitudinal direction (28) of the furnace (26). Said support bars (34, 35) form a plurality of descending sections (36, 37) down which the pipes (30) can roll. To each descending section (36, 37) is allocated a stop (40) which is provided at the end of a descending section and is fitted across the length (28) of the furnace (26). On rolling down the descending section (36, 37), the pipes (30) acquire sufficient kinetic energy, for them to be redirected across the longitudinal direction (28) on striking the stop (40).

Description

The invention relates to a method for continuous burning ceramic pipes and an oven for performing this procedure rens.

As is known, the ceramic material is only produced by firing. Green tubes are turned into ceramic tubes by burning them in the oven special stoneware pipes for sewers. During burning If there were no deviations in shape, this would occur in the finished Tubes to geometric errors, such as deflection, out-of-roundness or the like. Pipes in a kiln therefore moved so that formal errors can not occur. It is a process Ren for firing ceramic pipes in an oven in which the Pipes initially rest in the fork of Y-shaped supports, each two such supports are assigned to the tube. The carrier of each of the the sides are each driven by a chain. Within the Oven, at least in its high temperature zone, the pipes are over a elevated plateau or a slight slope rolled. Here they are from one leg of the Y-shaped carrier moves forward and remains in on lay on this thigh.

This process and the corresponding oven have fundamentally changed proven, but the disadvantage is the relatively high mechanical complexity. Of the Synchronization of the two beams on each tube is difficult to achieve, much more it happens that the two supports of a pipe are not on the same Height are so that the pipe is transported obliquely forward. this leads to to problems. In addition, this known method is only for pipes without  Exterior glaze and suitable without an integrated sleeve.

This is where the invention begins. It has set itself the task of To improve the method of the type mentioned and the accordingly to further develop the furnace so that the transverse orientation of the Pipes inside the furnace is always guaranteed.

This object is achieved by the method according to claim 1 and by the furnace according to claim 8.

The difference to the method of the type mentioned above is suitable the method according to the invention also for burning pipes with inte grommet and pipes glazed inside and out. The Trag rails form a multitude of slopes, the individual slopes Read paths are either arranged one after the other like sawtooth or are part of a continuous gradient. The slopes can be stationary and are preferably stationary, so that the left and the right guidance of a pipe always have the same position. If the pipes deviate from the transverse direction when rolling down a slope, is this deviation at the end of the downhill section again the stops balanced and the correct transverse position restored poses. To do this, the pipes must be off at the end of a downhill section have sufficient kinetic energy so that it attaches itself when struck automatically align the respective stop transversely to the longitudinal direction can. This kinetic energy should only be so large that the Alignment is safely achieved so that the bumps when striking the Keep the stroke low. The movement of the pipes should continue along the slopes take as much time as possible. Be accordingly the slopes are inclined so that the pipes roll safely is achieved without additional mechanical drives, but the flattest Angle at which such a rolling is achieved is selected.

The transport system according to the invention is essentially stationary. This means that errors in the synchronism of drive chains can no longer occur occur. Stoves of any length can be built.

According to the invention, the tubes are not continuously rolled, but rather alternate rolling and resting phases. The rest periods are time  Lich dimensioned sufficiently short that no permanent ver Formations of the pipes occur, in particular no deflection or changes of the cross section.

The tubes roll on two elongated, essentially parallel supports rails. They roll down the slopes down to a level blow and then get conveyed by a conveyor or automatically into the next slope. This way you can Manufacture well-glazed pipes as well as pipes with an integrated sleeve.

The pipes are transported through the furnace in cycles. At every bar a green tube is placed in the entrance of the furnace and one is done removed burnt tube. With each cycle, one is inside the oven Pipe transported from one downhill section to the next downhill section.

A procedure has proven to be particularly preferred in a high temperature zone of the furnace with a shorter one Cycle time, i.e. an increased cycle is worked. Go through the Pipe the same slope several times until it ends at the normal tak tes can be transported or rolled to the nearest slope. Accordingly, in the area of the high-temperature zone, circulation devices, those working at a higher clock rate are provided. Furthermore, the Devices of the high temperature zone designed so that they are either a Transport the pipe back to the beginning of the same slope or - at the end of the cycle - the pipe into the next gradient can transport or release.

The pipes should advantageously be at the beginning of a downhill section have a different direction of rotation than at the end of the slope. They have when rolling down the slope by an angle alpha ge turns, e.g. B. alpha = 70 ° or 180 °. The length of the downhill sections will be like this matched to the outside diameter of the tubes that the tubes each through the slopes and rolling down a certain amount Dimension alpha for the subsequent rest position and this dimension is selected so that the pipes always have different rotational positions take one. This allows the pipes to be hot plastic do not become out of round or bend. The support on the mounting rails is done in such a way that the pipes support in their gravimetric 1/4 points  will. The mounting rails are narrow, for example several centimeters up to a maximum of twenty centimeters, e.g. B. 10 cm, wide. Between the two Guideways are 50% of the total weight of the pipe, left and to the right of each tour is 25 percent by weight. Thereby the carrier rails have the least possible influence on the deformation pipe. They have a flat surface.

When the tubes are dipped in a glaze bath before entering the oven only those areas remain on the outside during the burning process coat unglazed, with which the pipes rest on the mounting rails. Advantageously, the tubes are immersed in the glaze bath gripped on the outside by pliers, which cover those areas in a ring and thus protect against access to the glaze bath with which the raw later lie on the mounting rails.

Further advantages and features of the invention result from the others Claims and the following description is not restrictive understanding embodiments that with reference to the drawing tion are explained in more detail. In this drawing:

Fig. 1 shows a schematic side view of an apparatus for firing ceramic pipes,

Fig. 2 is an interior view of a portion of the oven of Fig. 1 in side view,

Fig. 3 is a plan view of the arrangement according to Fig. 2,

Fig. 4 is a side view similar to Fig. 2 of another embodiment

Fig. 5 is a view similar to FIG. 3 of the embodiment according to FIG. 4, and

Fig. 6 is a side view of another embodiment.

Referring to FIG. 1 are suitable pipes, so-called green tubes 20 for burning; first immersed in a glaze bath 22 and then in the entrance area 24 of a furnace 26 , which is designed as an elongated furnace and is also referred to as a horizontal furnace. The furnace has a longitudinal direction 28 . In it there are pipes 30 , they lie inside the furnace 26 substantially horizontally and transversely to the longitudinal direction 28th The individual tubes 30 have a distance from one another in the longitudinal direction 28 , which is, for example, 10 cm to 1 m, the tubes 30 are located within the furnace 26 in one position. The burned pipes 30 leave the furnace 26 at an exit region 32 .

Inside the furnace 26 , the tubes 30 rest on support rails 34 , 35 . Two support rails 34 , 35 are provided, which run essentially parallel to one another. They support the pipes, the smallest possible area used for the support, so far the support rails 34 , 35 are for example a few cm wide, if possible they are even narrower, for. B. only 1 cm or less wide.

The support rails 34 , 35 form a plurality of slopes 36 , 37 lying one behind the other. 36 denotes the downhill sections outside a high-temperature zone 38 of the furnace 26 , with 37 the downhill sections inside this high-temperature zone 38 . In the area of the high temperature zone 38 , temperatures of a maximum of, for example, 1,100 to 1,280 ° C. are present. In this area, the tubes 30 become hot plastic, and improper handling can result in permanent deformation. According to the invention, the pipes are rotated again and again by rolling down slopes 36 , 37 . Due to stops 40 , which are each located at the end of a downhill section 36 , 37 , it is achieved that the pipes 30 are always found transversely to the longitudinal direction 28 when they have got into an inclined position due to the rolling.

The details of the furnace can be seen more clearly from the first exemplary embodiment according to FIGS. 2 to 3. Thereafter, the furnace 26 has an upper wall 42 , side walls 44 and a lower wall 46 . The side rails 34 , 35 are substantially sawtooth-shaped in a side view. The flattened sections form the slopes 36 , 37 , while the steeper and shorter sawtooth flanks form the stops 40 . Each slope section 36 and 37 is assigned a stop 40 . Each impact consists of a stop part, which the one mounting rail, for. B. 34 , is assigned and a second stop part, which is typically identical and the second mounting rail, for. B. 35 is assigned. At the stroke 40 is aligned so that the two stop parts are positioned exactly transverse to the longitudinal direction 28 .

In practical operation of the furnace 26 , the pipes 30 roll down a slope 36 until they strike the associated stop 40 . Due to their kinetic energy, they can align themselves transversely to the longitudinal direction 28 , if this is necessary at all, provided that a transverse error has occurred during the rolling movement. The tubes have an integrated sleeve 31 .

The furnace 26 operates in cycles. During a cycle, a new, green pipe 20 is conveyed into the entrance area 24 and a completely burned pipe 30 is removed from the exit area 32 . In each Ge slope section 36 , 37 there is a maximum of one pipe, optimal is an operating state in which as many slope sections 36 , 37 are filled with a pipe.

During a cycle, a tube 30 rolls at least once down a slope 36 or 37 , butts against the associated stop 40 , lingers there and is transported to the beginning of the next slope.

A cycle is thus composed of the following times or phases: 1st rolling phase, within this time the tube 30 rolls down the gradient 36 , 2nd resting phase, within this phase the tube 30 is at the stop 40 and 3rd transport phases, within these phases the tube is moved by devices to be explained.

The rolling of the tubes 30 serves to give the tubes a different orientation again and again. When rolling down the slopes 36 , 37 be the tubes each have a different rotational orientation. Otherwise presses 30 roll the pipes on its outer surface, and rotate at there through an angle which is not equal to 360 °, and is dimensioned as possible so that relationships at several successive gradients and thus Dre always different or opposite rotational orientations it ranges will. In this respect, angles of rotation of 70 ° or 180 °, for example, have proven to be particularly favorable.

One problem is that you want to use a furnace for several different pipes, for example for pipes with nominal widths of 150, 200 and 250 mm. The outer circumference is different for them, and accordingly the change in angle of the rotational orientation is different for a given rolling distance. The lengths of the downhill sections 36 , 37 and the transport processes are coordinated and selected in such a way that the occurring pipe diameters are rotated as optimally as possible.

A so-called transport device 48 is provided for the transport of a pipe 30 from a downhill section 36 , that is to say from a stop 40 at the beginning of a subsequent downhill section 36 . Furthermore, at least some of the gradients 37 located in the high-temperature zone 38 have a so-called circulation device 50 . It has the purpose of transporting a pipe 30 at least once, preferably more frequently, to the beginning of the same downhill section within one cycle, so that the pipe can at least partially pass through the downhill section 37 again. In this way, the rest periods are shortened. It is avoided that the tubes 30 bend in the hot plastic state within too long periods of rest or otherwise deform.

It is possible to combine the transport device 48 and the circulating device 50 in a common device, this is also the case in the exemplary embodiment according to FIGS . 2 and 3. Each slope is assigned a fork 52 , each support rail 34 , 35 is assigned such a fork 52 in the immediate vicinity. The two forks 52 can carry a tube 30 together.

The forks 52 have a substantially vertical support part which extends downwards through a slot 54 in the lower wall 46 , underneath the actual furnace there are the drive parts for the devices 48 , 50 in the normal temperature range. In the specific case of FIGS. 2 and 3, it is a vertically working lifting cylinder 56 , a lifting cylinder 56 per support rail 34 or 35 and per slope 36 or 37 is provided. His way to work is y. Furthermore, a horizontally operating lifting cylinder 58 , in this case several slopes can be operated together on a mounting rail 34 or 35 , as can be seen from FIG. 2, where a horizontal lifting cylinder 58 acts on a number of vertical lifting cylinders 56 and moves them together. His way to work is x.

The arrangement of the lifting cylinders 56 , 58 can be used both as a Transportvor device 48 , and as a circulation device 50 . As a trans port device 48 , it is used as follows. The tube 30 is located at the stop 40 . The fork is moved under the tube 30 , the tube is raised by operating the vertical lift cylinders 56 on each side. Now the tube is moved so far via the horizontal lifting cylinder 58 in Fig. 2 to the right until it is above the start of the following gradient 36 . By means of the vertical lifting cylinders 56 , the two forks 52 are lowered to such an extent that the tube comes to rest on this downhill section 36 . The forks 52 are pulled further down so that the tube 30 can roll down the slope 36 until the next stop 40 occurs.

As a circulation device and in the high-temperature zone 38 , the arrangement works as follows: The tube 30 is picked up as described above and lifted away from the mounting rail 34 upwards, but now to the left, transported back to the beginning of the same slope. For this purpose, who moves the horizontal lifting cylinder 58 accordingly, to the left in Fig. 2. In this way, the pipe 30 rolls down the same slope and comes to the associated stop 40 . Depending on the quality of the material of the tube 30 , 2, 3, 4 or more cycles are carried out per cycle. These cycles are only needed in the high temperature zone 38 of the furnace 26 , not in the other furnace areas. Experience has shown that the pipes become hot plastic above a temperature of more than 700 ° C, typically more than 800 ° C, and are then particularly sensitive to deformation. Due to the multiple revolutions within a downhill section 37 , the tubes 30 are moved sufficiently frequently that deformation cannot occur.

The exemplary embodiment according to FIGS. 4 to 5 is based on support rails 34 , 35 which extend over the entire length of the furnace 26 or over partial areas, for example a number of downhill sections, e.g. B. 8 to 12 Gefällestrec ken, have a constant slope. As can be seen from Fig. 4, the section of the furnace shown and possibly the entire furnace 26 is inclined with respect to the horizontal. As a result, the support rails 34 , 35 have a continuous gradient and the individual gradient sections 36 and 37 adjoin one another in a straight line.

In the exemplary embodiment according to FIGS. 2 and 3, the angle of inclination of the gradients 36 , 37 is chosen so that the pipes overcome the static friction and the rolling friction, that is to say always roll at any point where they are placed on the gradients 36 , 37 begin. In the exemplary embodiment from FIGS. 4 and 5, the inclination is lower. The tubes 30 do not roll by themselves, so the static friction is not overcome, but the angle is greater than that of the rolling friction. Once the tubes 30 are bumped and rolling, they continue to roll.

4 and 5 arms of transport devices 48 serve as stops in the embodiment according to FIGS . Each slope 36 and 37 are assigned two star arrangements, the two star arrangements of each support rail 34, 35 are rotatably connected to one another via a common shaft. The arms are arranged at a 120-degree angle to each other. The upstanding arm acts as a stop 40 . In Figs. 4 and 5 the position is shown, the tubes are in the 30 to its quiescent phases. Proceeding from this, the next movement processes proceed as follows: The star-shaped transport devices 480 rotate clockwise by 120 degrees. As a result, the arm that previously formed the stop 40 is folded down and no longer blocks the rolling movement of the associated tube to the right. The following arm strikes the pipe 30 from below and thus gives it an impulse and possibly moves it over a certain distance until the pipe 30 rolls down the following downhill section 36 or 37 and reaches the next stop 40 . This is formed by the now upright arm of the star-shaped transport device of the following gradient 36 and 37 .

A high-temperature zone 38 is shown on the right in FIGS. 4 and 5. In order to achieve several revolutions during one cycle, the Gefällestrec ken 37 of this zone are additionally equipped with tabs which can be raised via a vertically acting lifting cylinder 56 , this state is shown in FIG. 4. In the retracted state are not over the Ge drop line 37 before. The arrangement described works as follows:

If the tube shown on the far right in FIG. 4 lies against its associated stop and the circulating device 50 with the tab described is initially still drawn in, the lifting cylinder 56 is actuated and takes the tab of each of the two support rails 34 , 35 that shown in FIG. 4 Inclination. The pipe 30 now rolls to the left until it abuts the upright arm of the previous slope 36 . After a while, the lifting cylinder 56 is lowered again, the pipe can now roll to the right again, whereby it may receive a small impulse from the star-shaped transport device of the preceding downhill section 36 in order to trigger the rolling movement.

Similarly, the embodiment operates as shown in FIG. 6, except that here both the support rails 34, raised 35 over a certain number of gradients, for example 6 to 12 so that the transfer can now take place in the opposite direction, ie to the left, the raised position is shown in dashed lines in Fig. 6. Again, the star-shaped transport devices 48 can be used to trigger the rolling. This can be done both in the movement to the left and in the movement to the right. As can be seen from FIG. 6, the two support rails 34 , 35 are articulated at the left end, at the right end they are articulated to a piston rod of the vertically acting lifting cylinder 56 . As a result, the two inclination positions, which are shown in broken lines in FIG. 6, are achieved.

Claims (10)

1. Method for firing ceramic tubes ( 30 ), in which

• green tubes ( 20 ) are introduced into an oven ( 26 ), pass through the oven ( 26 ) transversely to the longitudinal direction ( 28 ) of the oven ( 26 ) and are removed from the oven ( 26 ) as finished, ceramic tubes ( 30 ),
• - The tubes ( 30 ) are conveyed through the furnace ( 26 ) in cycles,
• - The tubes ( 30 ) rest on two in the longitudinal direction ( 28 ) of the furnace ( 26 ) duri fenden support rails ( 34 , 35 ), the support rails ( 34 , 35 ) form a plurality of slopes ( 36 , 37 ) along which the Pipes can roll down and
• - Each slope ( 36 , 37 ) is assigned a stop ( 40 ) which is provided at the end of a slope ( 36 , 37 ) and is arranged transversely to the longitudinal direction ( 28 ) of the furnace ( 26 ), the tubes ( 30 ) when rolling down the slope ( 36 , 37 ) receive such sufficient movement energy that when struck against the respective impact ( 40 ) they can align themselves transversely to the longitudinal direction ( 28 ).

2. The method according to claim 1, characterized in that at least egg nige slope ( 36 , 37 ), preferably each slope ( 36 , 37 ) is associated with a transport device ( 48 ), the tubes ( 30 ) from a slope ( 36 , 37 ) in the next slope ( 36 , 37 ) moves or promotes. 3. The method according to claim 1, characterized in that there is a maximum of one tube ( 30 ) in each downhill section ( 36 , 37 ). 4. The method according to claim 1, characterized in that the tubes ( 30 ) rest on the mounting rails ( 34 , 35 ) so that outside each guide 1/4 of the total weight and between the mounting rails NEN ( 34 , 35 ) each Half of the total weight of the tube ( 30 ) be found. 5. The method according to claim 1, characterized in that the tubes ( 30 ) have an integrated sleeve ( 31 ). 6. The method according to claim 1, characterized in that the green tubes ( 20 ) are immersed in a glaze bath ( 22 ) before being introduced into the oven ( 26 ), preferably ring areas on the outer jacket of the tubes ( 30 ) to which the Contact with the mounting rails takes place, are covered when immersed. 7. The method according to claim 1, characterized in that the tubes ( 30 ) at the beginning of a slope ( 36 , 37 ) have a different rotational orientation than at the end of this slope ( 36 , 37 ), in particular that the tubes ( 30 ) to the The ends of successive slopes ( 36 , 37 ) have as different a rotation orientation as possible. 8. The method according to claim 1, characterized in that the furnace ( 26 ) has a high-temperature zone ( 38 ) that at least some of the water in the high-temperature zone ( 38 ) gradients ( 36 , 37 ) are equipped with circulation devices ( 50 ) and that the pipes ( 30 ) are transported back through this circulation device ( 50 ) to the beginning of the same downhill section ( 36 , 37 ) and roll down the downhill section ( 36 , 37 ) again. 9. Furnace ( 26 ) for firing ceramic tubes ( 30 ), which has an entrance into which green tubes ( 20 ) are introduced which pass through the furnace ( 26 ) transversely to the longitudinal direction ( 28 ) and which has an exit from which the finished ceramic tubes ( 30 ) are removed, two support rails ( 34 , 35 ) running in the longitudinal direction ( 28 ) being provided in the furnace ( 26 ), on which the tubes ( 30 ) rest and these support rails ( 34 , 35 ) form a plurality of downhill sections ( 36 , 37 ) along which the pipes ( 30 ) can roll down, each downhill section ( 36 , 37 ) being assigned a stop ( 40 ) which is provided at the end of the respective downhill section ( 36 , 37 ) and is arranged transversely to the longitudinal direction ( 28 ) of the furnace ( 26 ). 10. furnace ( 26 ) for burning ceramic tubes ( 30 ) according to claim 9, characterized in that each slope ( 36 , 37 ) is associated with a transport device ( 48 ) and at least the slopes ( 36 , 37 ) in the high temperature zone ( 38 ) a circulation device ( 50 ) is assigned.