JP2012040585A - Method of manufacturing annular roughly shaped material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of treating a ring-like roughly shaped material comprising a treatment condition for suppressing or closing an inner air gap generated in a ring in hot ring rolling processing.SOLUTION: In this method of manufacturing the ring-like roughly shaped material by hot ring rolling processing, when showing the constitution of the ring rolling in three dimensions comprising X-axis and Y-axis directions and a Z-axis direction, a main spindle 2 of a ring rolling machine is inclined at the same angle symmetrically with respect to the Y-axis to install pressurization parts 4 of two main rolls 3, 3 to abut on each other to form a V-shape having a fixed angle, and a steel material ring 12 is inserted to a caliber 8 between an outer peripheral face 5 of the pressurization part 4 and an outer peripheral face 7 of a mandrel 6. A value of f/V which is a ratio of peripheral speed V of the two main rolls 3, 3 with respect to reduction speed f of the mandrel 6 is controlled to be in a fixed range. By pressing force of the main rolls 3, 3 with respect to an outer face 9 and a lateral face 10 of the caliber 8 and reaction force of the outer peripheral face 7 of the mandrel 6 to an inner face 11 of the caliber 8, reduction of an outer peripheral face 13 of the steel material ring 12 is performed.

Description

  Using a ring rolling machine, the peripheral speed of the main roll against internal voids or voids that may occur or expand during hot rolling, or against internal voids or voids that exist before hot ring rolling The present invention relates to a processing method for suppressing the generation or expansion of internal voids, that is, voids, or by closing the internal voids, that is, voids, by controlling the relationship between the pressure and the mandrel reduction speed.

  In fields such as steel plate rolling, internal voids or voids are controlled by controlling the shape of the rolled material or controlling the rolling speed in addition to controlling the shape of the rolled material. It has been proposed to suppress generation and expansion, or to close an internal space, that is, a void by pressure bonding.

  As these, the technique of reducing an internal space | gap, ie, a void, is controlled by control of the shape of rolling materials, such as plate rolling of steel materials, and control of rolling speed. For example, a steel slab reduction method has been proposed in which the center porosity generated in continuous casting and present in the slab is completely crimped. (For example, refer to Patent Document 1). However, this method requires a water cooling on the surface of the slab in order to provide a temperature difference of 400 ° C. or more between the surface and the center of the slab, and the loss of the calorific value is large. Since the rolling is performed at a temperature difference of 400 ° C or more with respect to the center of the slab and the shape ratio is 0.5 or more, a rolling force that is several times that of normal rolling is required. There is a problem that the equipment cost is increased to increase the capacity. Furthermore, continuous cast slabs are rolled out in the rough rolling process, and in the finish rolling process, all of the multi-pass rolling and low-pass rolling are combined with heavy rolling under a shape ratio of 0.5 or more to form a heavy steel plate. The method of manufacturing and crimping | bonding a center porosity is proposed (for example, patent document 2). Furthermore, in the method for carrying out the method of Patent Document 2, a reduction amount of 0.5 to 2.0 mm / mm is provided between the liquidus crater tip and the solidus crater tip of the slab in the continuous drawing step of continuous casting. A method has been proposed in which the pressure is continuously reduced in a range of minutes and then the method of Patent Document 2 is performed (see, for example, Patent Document 3). These are aimed at improving the internal microporosity of the rolled sheet material. Has achieved. However, in the hot ring rolling process, a technique for improving internal voids, that is, voids, has not been established yet.

JP-A 61-238404 JP-A-2-55605 JP-A-2-55606

  The hot ring rolling method is a processing method in which the diameter of a ring is increased by reducing the thickness of a material using a plurality of rolls. This method has the advantage that the yield is good and the required processing force is small, and is a method widely used in the production of a ring-shaped material having a relatively large diameter. However, since this method is a processing method for expanding the diameter, tensile stress acts in the circumferential direction of the ring. This stress is caused by (1) voids that existed before processing, or (2) interfaces inside the workpiece, for example, interfaces between workpieces and inclusions that have a difference in deformation resistance. There is a case where the generation of voids is promoted during the ring rolling process or the voids are enlarged.

  This gap may cause the following problems. For example, when turning a forged product and then heat-treating it into a given bearing, if the gap is located on the surface of the forged product or just below the surface, using the bearing may cause early defects such as fatigue delamination There is. For this reason, in the hot rolling process, a process method or process conditions for suppressing or closing internal voids, that is, voids, are required.

  Accordingly, the problem to be solved by the invention of the present application is to provide a method for processing a ring-shaped material having processing conditions for suppressing or closing internal voids, that is, voids generated in a ring in hot ring rolling processing. .

  Means of the present invention for solving the above-mentioned problems is a method generally known as Saito-type ring rolling method in which ring rolling is performed between a main roll and a mandrel in the main roll. In the method of claim 1, when the three-dimensional representation of the horizontal X-axis direction, the vertical Y-axis direction, and the z-axis direction in the front direction is shown, the main axis of the ring rolling machine is contrasted with respect to the Y-axis direction. The pressurization part formed in the outer peripheral part of two main rolls inclining by the same angle is installed in contact with the V shape of a fixed angle. Subsequently, the steel ring of a raw material is penetrated in the hole type | mold formed between the outer peripheral surface of the pressurization part of these two main rolls, and the outer peripheral surface of a mandrel. Next, the value of f / V, which is the ratio of the peripheral speed V of the two main rolls to the rolling speed f of the mandrel in the relationship between the two main rolls and the mandrel, is controlled within a certain range. The outer peripheral surface of the steel ring was squeezed by the pressing force on the outer and side surfaces of the hole mold formed in the pressurizing part and the reaction force by the inner surface of the hole mold formed on the outer peripheral surface of the mandrel, and the steel ring was cut in the ring axial direction. A method for producing a ring-shaped element by hot ring rolling, wherein a steel ring having a ring cross section having a cross-sectional shape is formed.

The second means of the present invention is a fixed range for controlling the value of f / V which is the ratio of the peripheral speed V of the two main rolls to the rolling speed f of the mandrel which is the relationship between the two main rolls and the mandrel. Is in the range of 4 × 10 ^{−4 to} 60 × 10 ⁻⁴ , the method for producing a ring-shaped element by hot ring rolling according to the means of claim 1.

  When the main roll peripheral speed V changes depending on the position, the maximum value of the peripheral speed of the pressurizing part that contributes to the processing of the main roll is the main roll peripheral speed V, and the average value when the mandrel reduction speed f fluctuates over time Is adopted as the mandrel reduction speed f. The method of manufacturing a ring-shaped material by hot ring rolling according to the means of claim 2.

  According to the first aspect of the present invention, when the outer peripheral cross section of the steel ring is pressed from the X-axis direction, the Y-axis direction, and the Z-axis direction to the inner peripheral surface side of the steel ring, the relationship between the two main rolls and the mandrel is established. By controlling the value of f / V, which is the ratio of the peripheral speed V of the two main rolls to the mandrel rolling speed f, within a certain range, the formation of voids or voids in the obtained ring-shaped material is suppressed. Alternatively, the formed voids, that is, voids are closed, and early defects due to fatigue peeling caused by the voids when used as a bearing can be prevented.

Further, in the method of claim 2, in the method of claim 1, the value of f / V, which is the ratio of the peripheral speed V of the main roll to the rolling speed f of the mandrel, which is the relationship between the main roll and the mandrel, is 4 × 10 ^{−. By} controlling it within a certain range of ^{4 to} 60 × 10 ⁻⁴ , the formation of voids or voids in the ring-shaped material is suppressed or the formed voids or voids are closed to reduce the voids when used as a bearing. Early defects due to fatigue delamination as a cause can be further prevented.

  Furthermore, in the means of claim 3, when the main roll peripheral speed V changes depending on the position, the maximum value of the peripheral speed of the pressurizing portion is set to the main roll peripheral speed V, and when the mandrel reduction speed f fluctuates over time, By setting the average value of the mandrel reduction speed over time as the mandrel reduction speed f, the formation of voids or voids in the ring-shaped element can be suppressed or the voids or voids formed can be closed more accurately.

It is a typical side view of the ring rolling machine used for the ring rolling of this invention. It is a top view which shows typically the part of two main rolls of the ring rolling machine of FIG. 1, a ring-shaped raw material, and a mandrel.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated below with reference to drawings and a table | surface. The present invention is a method using the ring rolling machine 1 shown in FIG. The ring rolling machine 1 used in this method supports two main rolls 3 and 3, a mandrel 6, and a plurality of holding rolls 16 on a support frame 17 that supports the ring rolling machine 1. That is, as shown in the plan view of FIG. 2, this ring rolling machine 1 is a ring whose main axis 2 is the Y axis passing through the contact portions of the two main rolls 3 and 3 of the ring rolling machine 1 and the center of the mandrel 6. It consists of a rolling machine 1 and passes through the intersection of the main shafts 3a and 3a of the two main rolls 3 and 3 that incline and contact the two pressurizing parts 4 and 4, and is perpendicular to the Y axis. When the axis is the X axis, the main shafts 3a and 3a of the two main rolls 3 and 3 are inclined with respect to the Y axis by providing a constant angle with the X axis.

  The method of the embodiment of the present invention shown in these drawings is a method based on the following two conditions (1) and (2). First, the method (1) of the condition is the method according to claim 1 using the ring rolling machine 1 shown in FIG. 1 in the hot ring rolling process. The ring rolling machine 1 used in this method supports two main rolls 3 and 3, a mandrel 6, and a plurality of holding rolls 16 on a support frame 17 that supports the ring rolling machine 1. As shown in FIG. 2, a hole mold 8 formed between the outer peripheral surface 5 of the pressure unit 4 of the two main rolls 3 and 3 of the ring rolling machine 1 and the outer peripheral surface 7 of the mandrel 6 is processed. A steel ring 12 made of a material is inserted, the outer peripheral surface 5 of the pressurizing part 4 of the two main rolls 3 and 3 is brought into contact with the outer peripheral surface 13 of the steel ring 12 which is a workpiece, and the outer periphery of the mandrel 6 The surface 7 is brought into contact with the inner peripheral surface 14 of the steel ring 12, and a plurality of holding rolls 16 are brought into contact with the outer peripheral surface 13 of the steel ring 12 so that the diameter of the holding roll 16 is increased as the diameter of the steel ring 12 is increased. Ring rolling is performed while backing up the periphery of the steel ring 12 while retreating the outer surface.

  That is, in the case of the ring rolling process of the method (1), the peripheral speed V of the two main rolls 3 and 3 with respect to the rolling speed f of the mandrel 6 which is the relationship between the two main rolls 3 and 3 and the mandrel 6. The ratio f / V is controlled within a certain range, and the pressing force against the outer surface 9 and the side surface 10 of the hole mold 8 formed on the pressing portions 4 of the two main rolls 3 and 3 and the outer peripheral surface of the mandrel 6 The steel material having a ring cross section 15 made of the hole mold 8 having a cross-sectional shape of the steel ring 12 cut in the ring axial direction by reducing the outer peripheral surface 13 of the steel ring 12 by the reaction force of the inner surface 11 of the hole mold 8 formed in FIG. Formed on the ring 12.

Next, the method of the condition (2) is the method of the invention according to claim 2, and is a relation between the two main rolls 3 and 3 and the mandrel 6 contributing to the ring rolling, with respect to the rolling speed f of the mandrel 6. In the ring rolling method under the condition (1) in which the f / V value, which is the ratio of the peripheral speeds V of the two main rolls 3 and 3, is controlled within a certain range, this certain range is set to 4 × 10 ^{−4 to} 60 ×. The value is in the range of 10 ^−4, the pressing force against the outer surface 9 and the side surface 10 of the hole mold 8 formed on the pressure part 4 of the two main rolls 3 and 3, and the hole mold 8 formed on the outer peripheral surface 7 of the mandrel 6. By the reaction force by the inner surface 11, the outer peripheral surface 13 of the steel ring 12 is squeezed down, and a cross-sectional shape cut in the ring axial direction of the steel ring 12 is formed in the steel ring 12 having the ring cross section 15 made of the hole mold 8. is there.

  In the above condition (1), the entire ring region of the steel ring 12 that is the material to be processed is constrained by the hole mold 8 formed by the two main rolls 3 and 3 and the mandrel 6, and the steel ring 12 The cross section is pressed. In this case, the value of f / V which is the ratio of the peripheral speed V of the two main rolls 3 and 3 to the rolling speed f of the mandrel 6 which is the relationship between the two main rolls 3 and 3 and the mandrel 6 is within a certain range. Is controlling. Therefore, a hydrostatic pressure stress in the compression direction can be applied to almost the entire rolled portion of the steel ring 12, and generation of voids, that is, voids in the shaped material formed on the ring and expansion thereof can be suppressed. Note that the hydrostatic pressure stress is one of the indexes for evaluating the expansion or contraction of the void. If the hydrostatic stress is in the compression direction, the void is directed in the closing direction.

Next, in the condition (2), when the value of f / V which is the ratio of the peripheral speed V of the two main rolls 3 and 3 to the rolling speed f of the mandrel 6 is less than 4 × 10 ⁻⁴ , two Since the rolling speed f of the mandrel 6 with respect to the peripheral speed V of the main rolls 3 and 3 is too small, only the surface of the steel ring 12 that is the workpiece is processed, and the steel ring 12 that is the workpiece is processed. The reduction does not act on the inside of the film, and a tensile stress acts on the inside. On the other hand, when the value of f / V exceeds 60 × 10 ⁻⁴ , the rolling speed f of the mandrel 6 with respect to the peripheral speed V of the two main rolls 3 and 3 is too large, and thus the steel ring 12 that is a work material. Cannot be rolled into the two main rolls 3 and 3 and cannot be rolled.

  Therefore, when the above conditions (1) and (2) are satisfied, it is possible to suppress the tensile stress generated inside the steel ring 12 over the entire area of the steel ring 12 that is the workpiece, and the steel material. Formation and expansion of voids inside the ring 12, that is, voids, can be suppressed.

(Experimental example)
Rolling was performed using a steel ring 12 having an outer diameter of 182 mm, an inner diameter of 75 mm, and a width of 43 mm as a material before ring rolling. In this case, the peripheral speed V of the two main rolls 3 and 3 and the reduction speed f of the mandrel 6 were conditioned as shown in Table 1. An artificial gap having a diameter of 2 mm was provided inside the material of the steel ring 12 as a workpiece, and the steel ring 15 was subjected to rolling according to the conditions shown in Table 1 to investigate the expansion rate of the gap. Evaluation of the expansion rate of the investigated void was performed according to the following criteria, with the ratio of the cross-sectional area of the steel ring 12 before ring rolling and the cross-sectional area after ring rolling being the expansion rate.

  In Table 1, the evaluation criteria for the void enlargement ratio were the void enlargement ratio <100%, 100% ≦ the void enlargement ratio <125%, 125% ≦ the void enlargement ratio. In these, the case where the enlargement ratio of the gap is <100% is indicated as ◯, and this can be reduced. In this case, the void was directed in the closing direction. Further, the case of 100% ≦ gap enlargement ratio <125% is indicated as Δ, which indicates a slightly enlarged one. In addition, the case of 125% ≦ gap enlargement ratio is shown as x. The case where f / V is large and the rolling itself could not be performed is “unrollable”.

In the evaluation of voids in Table 1 of this experimental example, No. Since the rolling speed f of the mandrel 6 with respect to the peripheral speed V of the two main rolls 3 and 3 is large, the steel ring 12 that is a workpiece does not bite into the two main rolls 3 and 3. I could not do it. No. 2, no. 3 and no. 6 is the ratio of the peripheral speed V of the two main rolls 3 and 3 to the rolling speed f of the mandrel 6, and the f / V is 20 × 10 ^{−4 to} 60 × 10 ^−4. Thus, the evaluation of the void could be reduced by ○. No. 4 is that the ratio f / V of the peripheral speed V of the two main rolls 3 and 3 to the rolling speed f of the mandrel 6 is 4.2 × 10 ⁻⁴ , which is slightly over 4.0 × 10 ⁻⁴ . The expansion ratio of the voids was 100% or more and less than 125%, and the evaluation of the voids was slightly expanded by Δ. On the other hand, no. 5 and no. 7 is that the ratio f / V of the peripheral speed V of the two main rolls 3 and 3 to the rolling speed f of the mandrel 6 is less than 4.0 × 10 ⁻⁴ , so that the expansion ratio of the gap is 125% or more. Yes, since the gap was enlarged, the evaluation of the gap was x. This is considered to be because only the surface of the steel ring 12 was processed, and tensile hydrostatic stress was generated inside the workpiece.

DESCRIPTION OF SYMBOLS 1 Ring rolling machine 2 Main axis | shaft 3 Main roll 3a Main axis | shaft 4 Pressurizing part 5 Outer peripheral part 6 Mandrel 7 Outer peripheral surface 8 Hole type 9 Outer surface 10 Side surface 11 Inner surface 12 Steel material ring 13 Outer peripheral surface 14 Inner peripheral surface 15 Ring cross section 16 Holding roll 17 Support Frame

Claims (3)

  In the method of ring rolling between the main roll and the mandrel in the main roll, the main axis of the ring rolling machine is shown in three dimensions: the X direction in the horizontal direction, the Y direction in the vertical direction, and the z axis direction in the front direction. In contrast to the Y-axis direction, the pressurization part formed on the outer peripheral part of the two main rolls is in contact with the outer periphery of the two main rolls in a V-shape with a constant angle, and the pressurization part of the two main rolls and the mandrel Is a ratio of the peripheral speed V of the two main rolls to the rolling speed f of the mandrel in the relationship between the two main rolls and the mandrel. The value of / V is controlled within a certain range, and the ring outer peripheral surface is squeezed down by the pressing force by the outer peripheral surface of the hole type of the two main rolls and the reaction force by the inner surface of the hole mold on the outer peripheral side of the mandrel. Forming a cross-sectional shape A method for producing a ring-shaped formed and fabricated material by hot ring rolling process, characterized. The fixed range for controlling the value of f / V, which is the ratio of the peripheral speed V of the two main rolls to the reduction speed f of the mandrel, which is the relationship between the two main rolls and the mandrel, is 4 × 10 ^{−4 to} 60 The method for producing a ring-shaped element by hot ring rolling according to claim 1, which is in a range of × 10 ⁻⁴ .   When the main roll peripheral speed V changes depending on the position, the maximum value of the peripheral speed of the pressurizing part that contributes to the processing of the main roll is the main roll peripheral speed V, and the average value when the mandrel reduction speed f fluctuates over time Is adopted as the mandrel reduction speed f, The method for producing a ring-shaped body by hot ring rolling according to claim 2.

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