EP0243789B1 - Method for manufacturing moulds for continuous-casting machines - Google Patents

Description

The invention relates to a method and a device according to the preamble of claim 7 for the production of continuous molds for continuous casting machines, in which an abutment for an internal gauge block and / or shape of the mold to be produced is initially at one end of a pipe section made of copper or a copper alloy having formed mandrel, the mandrel for calibrating the pipe section is introduced into the pipe section, the pipe section is then ironed onto the mandrel by means of a die, and the mandrel is removed from the calibrated pipe section after the molding process.

Such a method has already become known in principle in the production of curved continuous molds for continuous arc casting machines (DE-PS 18 09 633). Here, a mandrel is pressed into a straight piece of pipe and has the inside gauge and shape of the mold to be produced, the outside dimensions of which are only a little less than the inside dimensions of the piece of pipe. The pipe piece is preformed according to the mandrel dimensions and then the mandrel and pipe piece are pressed together through a die in order to press the inner surfaces of the pipe piece tightly onto the mandrel. This process has proven itself to date, so it can be used to produce tubular molds of high dimensional accuracy and surface quality as well as hardness sufficient for use in continuous steel casting. Even though the quality of the tube molds manufactured according to the known process still corresponds to today's standard, the process itself requires a high level of mechanical and personnel expenditure, and there is no rational manufacturing technology.

In addition, to improve the efficiency of existing casting systems, more and more are being converted to larger molds. In order to reduce downtimes by changing the molds, it is necessary to increase the tool life. For this purpose, it is again necessary to increase the hardness of the mold materials used and to improve the dimensional accuracy of the molds used. The requirement for the processing of materials, in particular copper materials, increased hardness with improved shape accuracy of the molds means for the mold manufacturer the use of greater deformation and forming forces than were previously necessary in the process described at the outset.

In another known method (GB-A-21 51 162), a straight piece of pipe flanged at one end is brought into a bent shape in a separate working step in order to produce curved continuous molds, radial pressures being exerted on the outer surface of the piece of pipe. Thereafter, a mandrel having the inside dimensions and shape of the mold to be produced is inserted into the preformed pipe section and the pipe section is then molded onto the mandrel.

Starting from this prior art, the present invention is based on the object of making the production of continuous molds of any dimensions and cross-sectional shapes considerably more efficient and therefore more cost-effective, and at the same time increasing the quality of the end product, regardless of the pipe cross section, the wall thickness and the degrees of hardness of the mold materials used.

The object is achieved in that, according to claims 1 and 7, the die is continuously adjusted depending on the radius of curvature of the mandrel or the tool surfaces during the relative movement between the tube piece and the die during the forming process in the respective working position for the mandrel or tool surface.

With the method steps according to the invention, a more rational production with improved quality of the end product can be achieved. This applies in particular to the manufacture of mold tubes with larger spatial dimensions adapted to the requirements and from harder mold materials. The production process can be controlled semi-automatically and fully automatically according to the order, making the process independent of manual handling errors.

The course of the process allows an optional order processing within a given delivery program, whereby noteworthy interruptions due to changeovers are avoided. A prerequisite for the proper execution of the production program is a primary material store, which contains the number of preliminary tubes necessary for processing, possibly of different dimensions. These front pipes can be straight, but also pre-curved pipe sections. Drawn pipe lengths are advantageously used as the starting material from which the pipe sections are cut to length, but rolled or cast pipe lengths are also used, which are used as base materials for the pipe sections to be processed according to the invention.

To produce continuous molds for continuous casting machines, an abutment for the mandrel to be inserted is expediently first provided at one end of a pipe section. Such an abutment can be through the pipe end pass through the mandrel, but one end of the tube piece can also be sharpened accordingly to prevent the pin from being pushed or pulled through the tube piece when it is inserted. As part of the rational production According to the invention, however, it has proven to be particularly advantageous to couple one end of the pipe section for this purpose. Hitching here is understood to mean flanging the edges of the pipe section end inwards.

For the invention it is important that the forming of the tube piece to the mold tube, and in particular the cold forming, to achieve the required mold qualities, such as dimensional accuracy, surface quality of the inner surfaces forming the mold cavity, hardness of the tube walls, by means of a mandrel having the inside dimensions of the mold tube . As a rule, the mandrel will be pressed into the pipe section, this also applies if e.g. Bent mold tubes are to be produced and straight tube pieces are to be removed from the primary material store, into which a curved mandrel is to be inserted. Without deviating from the idea of the invention, one can of course also design the insertion of the calibration mandrel into the pipe section to be shaped such that the mandrel is guided with play in the pipe section, curved or straight, and the mechanical contacting takes place only during the forming process.

To achieve the desired mold qualities, a matrix is decisive for the invention, by means of which the thickened piece of pipe (mandrel-pipe-stucco combination) is ironed onto the mandrel, that is to say it is molded onto a mechanical surface. For this purpose, the flared pipe section can be pushed or pulled through the die, but in a further development of the invention one can also proceed in such a way that the die is moved over the fixed, flared pipe section for the purpose of pipe forming. The tight pressing of the inner surface of the pipe piece onto the mandrel enables the production of straight or curved, conical or partially conical mold pipes, which are characterized by a particularly high degree of dimensional accuracy, a high surface quality and a hardness sufficient for use in steel continuous casting, the method according to the invention being used ensures constant mold quality in a cost-effective way of working.

If, as is also provided in a further development of the invention, the die is continuously adjusted to the respective working position for the mandrel or tool surface as a function of the radius of curvature of the mandrel or the tool surfaces during the relative movement between the tube piece and the die during the shaping process, this measure leads despite higher forming forces, e.g. when forming a thorn-out piece of pipe onto the calibration mandrel, to a uniform decrease in material in the process sequence and thus to a uniform wall thickness that is free of internal mechanical stresses. These properties which can be achieved by the invention lead to a substantial extension of the service life. This applies in particular if, in carrying out the invention, the die is regulated continuously in the normal position to the mandrel or die surface as a function of the radius of curvature of the mandrel or the tool surfaces during the relative movement between the tube piece and the die during the shaping process.

In addition, the continuous adjustment of the die into the respective working position enables the die to be set in a targeted manner during the forming process, for example to compensate for wall thicknesses of non-uniform pipe pieces that are supplied as primary material to the forming device. Any angle settings, for example to the mandrel center axis, can be achieved. Known devices (DE-PS 21 54 226) and methods (EP-PS 0 060 820) do not offer these possibilities. The automatic infeed of the die in the direction of the curved mandrel can lead to uneven material removal and to the uneven wall of the mold tube. The pulling of the pipe section over an externally adjacent curved tool surface does not lead here either; in particular, the required dimensional accuracy of the inner surfaces of the mold tube cannot be achieved with this.

A particularly advantageous embodiment of the invention is obtained if, as already indicated, a curved mandrel having the inside dimensions and / or shape of the mold tube to be produced is introduced into the pipe section and the thorn pipe section is molded onto the mandrel by a pivotably mounted die. The fact that at any point in time of the relative movement between the thickened pipe section and the die is normal to the radius of curvature of the mandrel ensures a uniform deformation of the pipe wall. Because the forming process when "ironing" the pipe onto the mandrel is actively influenced at all times.

The relative movement between the pipe section, in particular the thickened pipe section, and the die is essential for the forming process according to the invention. Therefore, it is basically irrelevant for the forming process whether the pipe section is pressed through or pulled through the die. If there is a mandrel in the pipe section which has the inside gauge and / or shape of the mold to improve the dimensional accuracy of the shaping interior, then it can often be expedient to guide the die in the axial direction of the mandrel over the flared pipe section.

The invention provides yet another advantage. The raw material used, e.g. Drawn pipes, which are then cut to pieces, generally have a certain tolerance with regard to the eccentricity of the wall thickness. Through the targeted adjustment of the die when calibrating the mold tube according to the invention, it is possible to eliminate these irregularities resulting from the so-called front tube.

The die itself is guided, for example, in a so-called die holder. In carrying out the invention, therefore, the continuous adjustment to the normal position to the mandrel surface takes place by the force acting on the die holder, which is rotatably or pivotably mounted and holds the die in a stable position relative to the die holder. One becomes advantageous here in particular because of the high forming forces, adjust the die holder hydraulically into the respective working position, for example in the normal position to the radius of curvature of the mandrel or the tool surfaces.

In addition to high quality expectations, the economy of the forming process is also essential for the invention. For this reason, it is provided in a continuation of the inventive concept that the setting movement of the die in the respective working position to the surface of the mandrel or the tool surfaces takes place via a freely programmable control. Depending on the pipe dimensions, wall thicknesses, material properties, radii of curvature and the like, i.e. order-related parameters, the setting in the working position for the respective radius of curvature runs automatically according to a predetermined program.

Another advantageous possibility for carrying out the invention is that if the setting movement of the die into the normal position or into any other working position, which includes any setting angle between die and mandrel surface or tool surfaces, by an automatic control depending on a force measurement between the die holder and the machine frame he follows.

After the forming, which is preferably a cold forming, and expediently provides degrees of deformation between 15 and 25%, based on the initial cross section of the pipe section, if pipe sections which have already been adapted to the final dimensions and / or the final form are used as the starting material, the calibration mandrel is now made from the molded mold tube pushed out or pulled out. Possibly. the mold tube (calibrated pipe section) is cut to the final dimension and the attached pipe end, for example, is also cut off. The mold tube thus finished can then either be packaged and made ready for dispatch after the quality control has been carried out, but it can also be made up by mechanical processing before the quality control, i.e. for example the end faces of the mold tube can still be mechanically processed or retaining grooves can be milled into the tube wall from the outside.

The method according to the invention can be applied to any mold cross-sectional shapes, the prerequisite being a mandrel shape corresponding to the desired cross-sectional shape of the mold. In this way, circular, rectangular, square or polygonal shapes can be achieved in cross-section, as can T, double-T, U- or L-shaped cross-sectional profiles.

The mandrel required for the shaping in accordance with the desired cross-sectional shape can also be conically shaped in the implementation of the invention, one or more times, in order to ensure the conicity of the mold cavity that may be required. The mandrel can also be bent in order to ensure the use of tubular molds produced according to the invention also for continuous arc casting machines.

The different profile of the mold cavity can lead to undercuts in the shape of the calibration mandrel. In order to eliminate problems in pressing or pulling the mandrel out of the mold tube from the outset in such cases, it has proven expedient to divide the mandrel two or more times. The division of the mandrel can be longitudinal and / or transverse to the axial direction of the mold.

The invention will be explained in more detail with reference to the exemplary embodiments shown in FIGS. 1 to 6. 1 and 2 show the procedural sequence of the invention, while FIGS. 3 to 6 illustrate the specific case of regulating the die into the working position.

For the production of curved tube molds according to the invention, the tube piece 1 suitable for a given mold type is selected from a store of cut-to-length tube pieces SR, possibly of different dimensions and / or cross-sectional shapes, and fed to station I for coupling. This coupling, ie flanging the pipe end 2, expediently takes place after the supplied pipe section 1 has been clamped into a suitable press device by upsetting the one pipe end. The coupled pipe section 1 is conveyed to station II by means of a suitable transport device, and at the same time the calibration mandrel 3 predetermined by the order becomes removed from the mandrel stock SD and also fed to the station II, in which it is pressed in a kind of press bench, for example, into the still straight pipe section 1. The flared pipe section 1 inevitably takes on approximately the mandrel shape.

Another possibility is to take the already curved pipe section 4 from the storage stock SR, to couple it in station I and then to insert the curved mandrel 3 in station II, i.e. depending on the shape and size of the mandrel to slide in or push it into the pipe section.

Regardless of the assignment of pipe section and mandrel, namely straight - curved or curved - curved, the decisive forming process is carried out in station III. Here, the pipe section 1 is ironed onto the mandrel 3 with the aid of the die 5. In the embodiment shown, the thorned pipe section (1/3) is pressed through the die in the direction of the arrow, the inner surface 6 of the pipe section 1 being pressed tightly onto the mandrel surface. With the copy of the mandrel shape and the mandrel surface, this deformation of the tube wall simultaneously increases the hardness of the tube material.

For further processing of the now-shaped mold tube 1 ', i.e. if necessary, assembly and quality control, the mandrel 3 is removed from the mold tube 1 'in station IV. This is done, for example, as shown in the figure, by means of a scraper 7, which serves as an abutment for the mold tube 1 'when the mandrel 3 is pressed out of the mold tube 1' in the direction of the arrow.

After the mechanical separation of mandrel 3 and mold tube 1 ', as indicated in station V, mandrel 3 is again fed to station II or returned to mandrel storage SD after completion of a production batch. The transport section 8 is used for this purpose. If straight tube molds or tube molds with double-T profiles are provided in further production lots, the mandrel 9 or the mandrel version is used accordingly 10 fall back. The coupled end 2 is separated from the calibrated pipe section 1, now the mold pipe 1 ', and the pipe, if the ends need not be machined or cut to a required final dimension, is fed to the test station P. The mold tube 1 'can then be packed and made ready for dispatch.

2 illustrates the work system according to the invention in a type of block diagram. In accordance with the work specification, for example, production batch of tubular mold, format XY square, material CuCrZr, partially conical, controlled, a suitable piece of pipe is removed from the storage feeder SR and fed to station I for coupling. In the meantime, the mandrel corresponding to the production batch defined in accordance with the work specification arrives from the mandrel storage SD at station II and is introduced into the coupled pipe section brought up by station I. The tube-mandrel combination then arrives in station III for tightly pressing the pipe section onto the mandrel surface and finally for separating the mandrel and now calibrated pipe section (pipe mold) to station IV.
From here, the calibrated pipe section is fed to the test station P, if necessary after prior finishing, cutting to length, etc., and the mandrel first arrives at the control station ST, which, depending on the scope of the production batch (number of the same mold type), either ensures that The mandrel arrives again in station II or is returned to the memory SD when the mold type to be manufactured is subsequently changed.

Details of the forming process are shown in FIGS. 3 to 6 on an enlarged scale compared to FIGS. 1 and 2. The raw material used for forming a tube piece into the mold tube is the bright drawn straight copper tube 11, for example made from an extruded round tube by tube drawing, with a Brinell hardness of, for example, HB 55-75. This tube is cut to the desired mold length, taking into account a machining allowance. Then, as can be seen from FIG. 3, the According to the internal dimensions of the mold to be produced, for example, a hard-chromed mandrel 12, which is deformed in accordance with the curvature of the circular arc continuous casting machine, is pressed (thorned) into the tube 11, as illustrated in FIG. 4.

Deviating from this, the copper tube 11 can of course already be pre-bent according to the mandrel shape in order to facilitate the insertion of the mandrel, and a sufficient clearance between the mandrel surface and the inner tube surface can also be selected for the same purpose. The copper tube 11 will conveniently be coupled to the end 13, i.e. flare the pipe end inwards to create an abutment for the inserted mandrel for the subsequent forming. The abutment can also be created by a bolt extending transversely through the end of the copper tube or simply by tapering the end of the tube 13.

5, the thorned copper pipe 11 is then fed to the forming device 14, which essentially consists of the machine frame 15 and the die holder 17, which is mounted on the machine frame 15 by means of the schematically indicated rotating or pivoting device 16 and which contains the die 18 contains. With 19 against the machine frame 15 supporting hydraulic cylinders are designated, which pivot the die holder 17, as indicated by arrows, relative to the machine frame 15 when actuating a corresponding control.

In this way, it is possible, as shown in FIG. 6, to set the ideal position, ie the normal position of the die to the mandrel surface, for example at any time when the thickened copper tube 11 is being passed (pulled or pressed) through the die 18. The ongoing forming process of tightly pressing or ironing the copper tube 11 onto the mandrel 12 can thus be actively influenced in the sense of a uniform wall thickness and in the sense of a uniform stress distribution and improvement of the mold life. This option is particularly useful when one goes to larger dimensions and harder mold materials.

The pushing together of copper pipe 11 and mandrel 12 through the corresponding to the mandrel curvature in the embodiment in the normal position, i.e. in each case perpendicular to the mandrel surface, regulated die 18 provides an unconditional dimensional accuracy of the mold 11 'thus produced because of the cold forming that takes place here, the Brinell hardness is simultaneously increased from the original to HB 80-110.

As further indicated in FIGS. 5 and 6, the respective position of the die 18 relative to the mandrel surface can be regulated with the aid of force measuring devices 20, which are arranged at different locations on the die holder 17 between die holder 17 and machine frame 15. The differences between the measured forces occurring are evaluated in data processing 21, for example via microprocessors known per se, and converted into control commands for regulating the die into the normal position. This enables the forming process to be optimized automatically based on the data specified in the order, namely for a wide variety of dimensions, cross sections, wall thicknesses, etc., for a wide variety of shapes and material qualities.

Claims (10)

1. A process for the production of continuous casting moulds for continuous casting machines, wherein firstly an abutment for a mandrel, which possesses the final internal dimensions and/or shape of the mould which is to be produced, is formed onto one end of a pipe section made of copper or a copper alloy, the mandrel is introduced into the pipe section for the calibration of the pipe section, the pipe section is then smoothed onto the mandrel by means of a die, and following the forming process the mandrel is removed again from the calibrated pipe section, characterised in that during the forming process the die (5;18) is continuously adjusted into the respective operating position relative to the surface of the mandrel or tool in dependence upon the radius of curvature of the mandrel (3; 12) or the tool surfaces during the relative movement between the pipe section (1;4;11) and the die (5;18).
2. A process as claimed in Claim 1, characterised in that during the forming process the die (5;18) is continuously adjusted into the respective position normal to the surface of the mandrel or tool in dependence upon the radius of curvature of the mandrel (3;12) or the tool surfaces during the relative movement between the pipe section (1;4;11) and the die (5;18).
3. A process as claimed in Claim 1 or 2, characterised in that the continuous adjustment of the die (5;18) into the respective operating position is carried out by applying force to the die holder (17) which is rotatably or pivotably mounted and maintains the die (5;18) in a stable position relative to the die holder (17).
4. A process as claimed in one of Claims 1 to 3, characterised in that the die holder (17) is adjusted hydraulically or mechanically into the respective operating position.
5. A process as claimed in one of Claims 1 to 4, characterised in that the adjusting movement of the die (5; 18) into the respective operating position is carried out via a freely programmable control arrangement.
6. A process as claimed in one of Claims 1 to 5, characterised in that the adjusting movement of the die (5; 18) into the respective operating position is carried out by automatic regulation in dependence upon a force measurement between the die holder (17) and the machine frame (15).
7. A device for the production of continuous casting moulds for continuous casting machines, comprising a mandrel, which can be introduced into a pipe section and which possesses the final internal dimensions and/or shape, and a die by which the pipe section passing through it is formed onto the mandrel, characterised by a rotatably or pivotably mounted die (5;18) with an adjustment facility hydraulically actuated in dependence upon control signals.
8. A device as claimed in Claim 7, characterised in that the mandrel (3;9;10;12) possesses a shape which is conical or partially conical in the longitudinal direction.
9. A device as claimed in Claim 7 or 8, characterised in that the mandrel (3;9;10;12) is doubly or multiply divided.
10. A device as claimed in Claim 9, characterised in that the division of the mandrel (3;9;10;12) extends longitudinally and/or transversely relative to the axial direction.

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