Hot steel forging in horizontal press

Abstract

The present disclosure relates to a steel forging process, in particular a hot steel forging process in horizontal press of a metal tube, preferably a cylindrical steel tube.

Claims

1. A forging process for obtaining a part from changing of a metal tube shape, wherein a portion of the part to be obtained is 2 to 2.1 times the a diameter and thickness of the metal tube, comprising the following steps: heating a portion of the metal tube meant to be changed in shape to have an end heating temperature between 1300° C. and 1400° C.; pressing the heated portion for bringing the heated portion closer to a pre-defined geometry of the part to be obtained; and subjecting the heated and pressed portion of the part to a second pressing for obtaining the portion of the part to be obtained with the pre-defined geometry of the part to be obtained; subjecting the heated and pressed portion of the part to a third pressing for obtaining the portion of the part to be obtained with the pre-defined geometry of the part to be obtained; selectively subjecting the heated and pressed portion of the part to a fourth pressing for obtaining the portion of the part to be obtained with the pre-defined geometry of the part to be obtained; wherein the pressing is performed by a horizontal-type press, wherein the partially heated metal tube is subject to radial deformation to obtain a difference ranging from 2 to 2.1 times of the diameter, or thickness, or the diameter and the thickness of the metal tube to be changed in shape, wherein the metal tube is a steel tube, wherein the partial heating of the steel tube is made in an electric induction oven, and wherein forging the partially heated steel tube is carried out in 60 seconds.

2. The forging process according to claim 1, wherein the metal tube is a cylinder.

3. The forging process according to claim 1, further comprising a controlled cooling of the metal tube.

4. The forging process according to claim 3, wherein the controlled cooling of the steel tube at a temperature between 900-1000° C.

5. The forging process according to claim 3, further comprising passing the part through a cooling tunnel with a speed variation of a conveyor belt and a flow rate variation of forced air passing therethrough.

6. The forging process according to claim 3, further comprising passing the part through a cooling tunnel on a conveyor belt, wherein the conveyor belt speed varies between 5-20 m/h.

7. The forging process according to claim 3, further comprising passing the part through a cooling tunnel wherein the flow rate of air charged inside the tunnel varies between 100-300 m.sup.3/h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For an easier understanding of the solution, drawings are herein attached, which represent preferred embodiments of the disclosure and which, however, are not intended to limit the scope of the present disclosure.

(2) FIG. 1: Flowchart of the hot steel forging process in horizontal press.

(3) FIG. 2: Side perspective of the starting cylindrical steel tube.

(4) FIG. 3: Side perspective of the starting cylindrical steel tube, wherein: 1 represents the tube area subject to heating; 2 represents the tube area not subject to heating.

(5) FIG. 4: Side perspective of the cylindrical steel tube placed inside the die with the heated cylindrical steel tube wherein: 3 represents the die.

(6) FIG. 5: Front perspective of the die with preform.

(7) FIG. 6: Top side perspective of the final die with preform.

(8) FIG. 7: Top side perspective of the final part with final part.

(9) FIG. 8: Top perspective of the starting cylindrical steel tube.

(10) FIG. 9: Side perspective of the heated starting cylindrical steel tube.

(11) FIG. 10: Side perspective of the tube with the second preform.

(12) FIG. 11: Side perspective of the final tube with burr.

(13) FIG. 12: Side perspective of the tube without burr wherein (a) represents the thickness of the part obtained after the herein disclosed forging process.

DETAILED DESCRIPTION

(14) Obtaining a part by a hot steel forging process in horizontal press, wherein the obtained part does not need machining and is not cracked, is carried out by performing three or four stages: heating the raw material or tube, preferably a cylindrical steel tube; three-stage forging the portion of the partially heated tube meant to be changed; deburring the scrap produced and optional controlled cooling of the forged part.

(15) The first stage for obtaining a part by a hot steel forging process in horizontal press covers heating the tube, preferably a cylindrical steel tube. In a preferred embodiment, the raw material as a tube, preferably a cylindrical steel tube, is partially heated in an electric induction oven. Thus, only the length of the tube, preferably a cylindrical steel tube, which is intended to deform by hot steel forging in horizontal press is heated, the remainder portions remaining unchanged since being very close to room temperature.

(16) During this first stage, the time and end heating temperature are monitored and adjusted according to the intended configuration of the final part. This monitoring is particularly important, since it ensures the uniformity of the process both in subsequent deformation of the raw material and in the chemical composition of the final part. In order to obtain the necessary deformation of the raw material, it is heated to a temperature ranging 1300-1400° C.

(17) The second step of the hot steel forging process in horizontal press consists in forging the raw material or partially heated cylindrical steel tube. During this stage the following stamping steps must be performed: increasing the diameter, thickness or diameter or thickness of the partially heated cylindrical steel tube; bringing it closer to the final geometry of the part; and stamping the part to its final geometry.

(18) The increase in the diameter, thickness, or the diameter and thickness of the partially heated cylindrical steel tube takes place in order to facilitate the subsequent shaping of the part. Thus, the partially heated cylindrical steel tube is subjected to radial deformation in order to obtain a diameter difference close to that of the intended final part, this difference ranging from 1.5-2.5 times the original size, in particular ranging between 1.5-2.5 times the diameter, thickness, or the diameter and thickness of the starting tube, however the various operations must be controlled to prevent defective or with lower mechanical stiffness products, etc. . . . . In cases where the diameter of the cylindrical steel tube is close to the diameter intended to be deformed, this first step—diameter increase of the partially heated cylindrical steel tube—can be avoided. In cases where the thickness of the cylindrical steel tube is close to the thickness intended to be deformed, this first step—thickness increase of the partially heated cylindrical steel tube—can be avoided.

(19) The second step of the stage for forging the partially heated cylindrical steel tube is characterized by bringing it closer to the final geometry, distributing it into the correct proportion so as to perfectly fill in in the third step. In this step the concentricity of the tool is essential so that the material is distributed properly, thereby avoiding subsequent problems with burrs or filling flaws.

(20) In the third step of the stage for forging the partially heated cylindrical steel tube, the tool has the geometry of the final part, thereby allowing the intended part to be obtained after stamping in this position. In order to obtain a deformation as perfect as possible while simultaneously avoiding premature wear of the tool, the three operations must be performed within a period not exceeding preferably 180 seconds, preferably 120 seconds, preferably not exceeding 60 seconds, or even more preferably not exceeding 15 seconds.

(21) Thus, by performing of the steps characterizing the forging stage, forging of the raw material, or the partially heated cylindrical steel tube, the partially heated cylindrical steel tube is subjected to three different pressings/deformations/stamping up to the obtention of the final part. These deformations are obtained by closing a tool with three different dies, caused by movement of a horizontal press. Thus, the final part is obtained after the starting cylindrical steel tube undergoing the three different positions of the tool, within a time which should preferably be less than 180 seconds, less than 120 seconds, less than 60 seconds, less than 30 seconds or less than 15 seconds.

(22) In a preferred embodiment, the deburring stage may be optional and may be performed when removal of the scrap produced during the previous steps is required.

(23) In a preferred embodiment, the cooling stage of the hot steel forging process in horizontal press may be optional. The cooling is controlled after forging operation, the part is removed from the tool at about 900° C., and depending on subsequent operations, and the part is cooled according to the applicability thereof.

(24) In a preferred embodiment, the controlled cooling of the part has also the function of avoiding a subsequent heat treatment of the part, should the required mechanical properties be provided by cooling. Defining the cooling process depends on the quality of the raw material, part size and, as mentioned above, the applicability thereof.

(25) In a preferred embodiment, the cooling process is defined by controlling the temperatures at a cooling tunnel inlet and outlet. Since this part shall be subsequently machined, cooling the part is intended to be slow, so as to cause normalization. For this purpose, the tunnel conveyor belt speed is caused to vary between 5-20 m/h, preferably 10-15 m/h and the flow rate of forced air flow passing therethrough may vary between 100-300 m.sup.3/h preferably 120-290 m.sup.3/h, and combinations thereof. The definition of these parameters is validated through multiple destructive and non-destructive mechanical testing of the parts after the cooling step.

(26) Although the present disclosure has only shown and described particular embodiments of the solution, one skilled in the art shall know how to introduce modifications and replace some technical features for equivalents, depending on the requirements of each situation, without departing from the scope of protection defined by the appended claims.

(27) The embodiments presented are combinable. The following claims set out particular embodiments of the disclosure.