Roll stand

Abstract

A roll stand, wherein at least two rolls for forming a workpiece are accommodated in the stand, and wherein a rolling force acting during the forming is supported by the roll stand, wherein the roll stand is produced by means of additive manufacturing.

Claims

1. A roll stand, comprising: at least two rolls for forming a workpiece are accommodated in the stand, wherein a rolling force acting during the forming is supported by the roll stand, wherein the roll stand is produced by means of additive manufacturing, wherein the additive manufacturing is performed indirectly, wherein the roll stand is formed at least partially as a cast part and a casting mold of the roll stand is produced directly by additive manufacturing, or wherein the roll stand is formed, at least partially, directly by additive manufacturing, wherein the stand sides are integrally interconnected by transverse struts made of a uniform material, a first transverse strut extending between the stand sides relative to a longitudinal axis of the stand sides and a second transverse strut extending between the stand sides perpendicular relative to the first transverse strut, wherein the transverse struts are produced jointly with the stand sides by additive manufacturing.

2. The roll stand as claimed in claim 1, wherein the roll stand is formed as a unit which is drivably movable in the course of a rolling procedure.

3. The roll stand as claimed in claim 2, wherein the roll stand is formed as a cold pilger roll stand.

4. The roll stand as claimed in claim 3, wherein at least one crank pin for moving the roll stand is accommodated on the roll stand, wherein in particular the crank pin is not formed by means of additive manufacturing.

5. The roll stand as claimed in claim 1, wherein the roll stand includes two stand sides, wherein the rolls extend between the stand sides and are mounted in the stand sides.

6. The roll stand as claimed in claim 1, wherein a shape of the roll stand is optimized with regard to mass and/or strength by a computer optimization using the finite element method.

7. A method for improving an existing rolling mill, comprising: a. recording framework parameters of the existing roll stand of claim 1; b. designing a roll stand optimized with respect to at least one property while maintaining the framework parameters recorded in step a.; c. manufacturing a new roll stand by additive manufacturing, and d. replacing the existing roll stand with the new roll stand.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred exemplary embodiment of the invention will be described hereafter and explained in greater detail on the basis of the appended drawings.

(2) FIG. 1 shows a three-dimensional view of a cold Pilger roll stand having installed rolls according to the prior art.

(3) FIG. 2 shows a three-dimensional view of a cold Pilger roll stand according to the invention, which can replace the roll stand from FIG. 1.

(4) FIG. 3 shows a further three-dimensional view of the roll stand from FIG. 2.

(5) FIG. 4 shows a view from the side of the roll stand from FIG. 2.

(6) FIG. 5 shows a further three-dimensional view of the roll stand from FIG. 2.

DETAILED DESCRIPTION

(7) The previously known roll stand shown in FIG. 1 of a cold Pilger rolling device comprises two stand sides 1′, 2′, which are assembled by a number of separate connecting bolts 3 to form a stand. The roll stand is drivably movable as a whole, wherein retaining elements for the movable mounting on a stationary rail system (not shown) are provided in a lower region. Connecting rods of a drive unit (not shown) engage on bearings 5 to drive the roll stand. The bearings 5 are accommodated on crank pins 6, which are in turn fixed in receptacles 6a in the stand sides 1′, 2′. The roll stand is alternately moved translationally at a defined stroke frequency by the connecting rods.

(8) At least two rolls 7, 8 are accommodated or mounted in the stand sides 1′, 2′. A rotation of the two rolls 7, 8 is coupled via gear wheels 9 and stationary toothed racks (not shown) to the translational movement of the roll stand.

(9) A tubular workpiece (not shown) runs between the rolls 7, 8 and over a mandrel (not shown). Forming according to the cold Pilger rolling method is performed in a known manner by the alternating movement of the roll stand in conjunction with a corresponding guide of the workpiece. In this case, the rolling force occurring between the rolls 7, 8 is supported by the roll stand 1′, 2′, 3.

(10) In the present example, the previously known roll stand 1′, 2′, 3 (without rolls and further fittings) has a mass of approximately 890 kg. The alternating movement takes place at a maximum stroke frequency of 200 strokes per minute.

(11) FIG. 2 to FIG. 5 show a roll stand 10 according to the invention made of cast iron. The shape of this roll stand 10 was optimized on a computer with aid of the finite element method to minimize the mass of the stand at given strength.

(12) Known framework data for the dimensions and minimum strengths of the previously known roll stand 1′, 2′, 3 were the starting point for the optimization. The shape of the stand was then optimized by means of the finite element method. One criterion in the optimization was that the stand is supposed to be castable in principle, nearly complete design freedom prevailed in the production of the casting mode with respect to undercuts, etc.

(13) As a specification, the achievable stroke frequency was increased to 250 strokes per minute. This required a reinforced design, in particular of the regions around the crank pins 6. The production of the computed stand according to FIG. 2 through FIG. 5 was then performed via indirect additive manufacturing. In this case, the casting mold was produced by a facility for 3D printing by additive manufacturing. The roll stand 10 was then cast by means of this additively manufactured casting mold. In the present case, cast iron was used as the casting material.

(14) The roll stand 10 manufactured in this manner had a mass of approximately 800 kg and increased strength in spite of the stroke frequency, which was increased to 250 strokes per minute.

(15) According to a method according to the invention for improving existing rolling mills, the existing stand 1, 2, 3 shown in FIG. 1 of an existing rolling mill in operation was replaced by the new stand 10. Because of the reduced stand mass, this generally permitted an increase of the stroke frequency of the rolling mill, without the drive device having to experience significant modifications.

(16) The crank pins 6 are also provided in the additively manufactured roll stand 10 as separate components which are fixed in receptacles 6a. These crank pins and the receptacles 6a thereof are among the most strongly mechanically strained points of the roll stand. The shaping ascertained by the finite element method resulted in a bionic shaping of the roll stand 10 having many rounded regions. In particular critical points such as the region around the receptacles 6a of the crank pins 6 are relatively reinforced in this case. In less critical regions, it was possible to thin out and save the stand material.

(17) In contrast to the conventional roll stand 1′, 2′, 3, stand sides 1, 2 of the roll stand 10 according to the invention are connected by means of integrally formed transverse struts 11 made of uniform material. The transverse struts 11 are produced together with the stand size 1, 2 by the (indirect) additive manufacturing and/or by the casting procedure.

(18) The rolls 7, 8 are understood in the present case as a unit rotatably accommodated in the roll stand 10, which is formed from a roll shaft and a roll body (not shown) attached thereon. A tool surface for executing the rolling procedure is formed by the roll body as a tool. The roll body is formed as a replaceable component. The connection to the roll shaft is produced in the present case by shrinking of the roll body onto the roll shaft. If the roll body is detached from the roll shaft, the roll shaft can be removed laterally from the roll stand 10. It is thus not necessary to separate the stand sides 1, 2.

(19) It is obvious that the above-described roll stand can also be produced by direct additive manufacturing. The properties of the additively joined stand material are to be taken into consideration accordingly in the computed shaping.

LIST OF REFERENCE SIGNS

(20) 1′ first stand side of prior art 1 first stand side according to the invention 2′ second stand side of prior art 2 second stand side according to the invention 3 connecting bolt 4 retaining element 5 bearing for drive unit 6 crank pin 6a receptacle for crank pin 7 first roll 8 second roll 9 gear wheel for roll drive 10 additively manufactured roll stand 11 integral transverse struts made of uniform material