阅读说明：本技术 用于轧制空心体或各种凹入的杆状体的轧制轧机 (Rolling mill for rolling hollow bodies or various recessed rod-shaped bodies ) 是由 安尼巴莱·布奇 切萨雷·拉维奥萨 A·达历山德罗 于 2018-03-01 设计创作，主要内容包括：一种用于轧制空心体或各种凹入的杆状体(特别是管,特别是无缝管)的轧制轧机,所述轧制轧机包括轧制区段(10),该轧制区段具有连续布置以限定轧制轴线Y的多个轧机机架和/或轧制模具(11),所述轧制轧机进一步包括移动装置,该移动装置用于使心轴(20)和装配在所述心轴(20)的端部部分(22)上的管状坯件(21)沿着轧制轴线移动并且连续地移动通过所述轧机机架或轧制模具(11)；其中所述移动装置被构造成通过在所述心轴上施加牵引力使所述心轴(20)和所述坯件(21)沿着所述轧制轴线Y移动并且连续地移动通过所述轧机机架或轧制模具(11)。(A rolling mill for rolling hollow bodies or various concave rod-shaped bodies, in particular tubes, in particular seamless tubes, comprising a rolling section (10) having a plurality of rolling stands and/or rolling dies (11) arranged in succession to define a rolling axis Y, said rolling mill further comprising moving means for moving along the rolling axis and successively through said rolling stands or rolling dies (11) a mandrel (20) and a tubular blank (21) fitted on an end portion (22) of said mandrel (20); wherein the moving means are configured to move the mandrel (20) and the blank (21) along the rolling axis Y and continuously through the rolling stand or rolling die (11) by applying a traction force on the mandrel.)

1. A rolling mill for rolling hollow bodies or various recessed rod-shaped bodies, comprising a rolling section (10), said rolling section (10) having a plurality of rolling stands and/or rolling dies (11) arranged in succession to define a rolling axis Y, further comprising movement means for moving a spindle (20) and a hollow blank (21) fitted on an end portion (22) of said spindle (20) along said rolling axis Y and in succession through said rolling stands or rolling dies (11); characterized in that said movement means are configured to move said mandrel (20) and said blank (21) along a rolling direction parallel to said rolling axis Y and continuously through said rolling stand or rolling die (11) by exerting a traction force on said mandrel (20).

2. The rolling mill according to claim 1, characterized in that said movement means comprise an engagement operating head (30), said engagement operating head (30) being switchable between a first release configuration and a second engagement configuration and being adapted to engage and selectively release a shank (23) integral with said end portion (22) of said mandrel (20), wherein when said operating head (30) is in said second engagement configuration and engaged on said shank (23), a movement of said engagement operating head (30) along a direction parallel to said rolling axis Y causes translation of said mandrel (20) and blank (21) along said rolling axis Y and continuous movement through said rolling mill stand or rolling die (11).

3. A rolling mill according to claim 2, characterized in that said joining operating head (30) comprises at least one first rocker arm (31), said at least one first rocker arm (31) being adapted to be switched to pivot between a first position and a second position, and the switching of said at least one first rocker arm (31) from said first position to said second position causes the operating head (30) to switch from said first release configuration to said second joining configuration, while the switching of said at least one first rocker arm (31) from said second position to said first position causes the operating head (30) to switch from said second joining configuration to said first release configuration.

4. A rolling mill according to claim 3, characterized in that it comprises switching means for selectively switching said at least one first rocker arm (31) between said first and second positions.

5. A rolling mill according to claim 4, characterized in that said at least one first rocker arm (31) is hinged on a point integral with a drawbar (40) of said moving device, said drawbar (40) being at least partially housed in a tubular jacket (50), said tubular jacket (50) being translatable with respect to said rod (40), and translation of said tubular jacket (50) with respect to said drawbar (40) in a first translation direction causing said at least one first rocker arm (31) to switch from said first position to said second position, while translation of said tubular jacket (50) with respect to said drawbar (40) in a second translation direction opposite to said first translation direction causing said at least one first rocker arm (31) to switch from said second position to said first position.

6. A rolling mill according to claim 5, characterized in that it comprises first translation means for translating the tubular jacket (50) with respect to the drawbar (40) in said first translation direction.

7. Rolling mill according to claim 6, characterized in that said first translation means comprise a first fixed switching station (60) defining at least one first engagement surface (61) and at least one second rocker arm (80) hinged on a point integral with said drawbar (40), wherein translation of said drawbar (40) along a translation direction parallel to said rolling direction and in a first translation direction causes said at least one first engagement surface (61) to be switched by said at least one second rocker arm (80) and said at least one second rocker arm (80) to be switched from a first position to a second position, and switching of said at least one second rocker arm (80) from said first position to said second position causes said tubular jacket (50) to be switched with respect to said lever (40) in said second translation direction opposite to said first translation direction Translate and, thus, cause the head (30) to switch between the second engagement configuration and the first release configuration.

8. The rolling mill according to claim 7, characterized in that said first translation means comprise means (62) for switching said at least one first engagement surface (61) of said first fixing station (60) to a release position by said at least one second rocker arm (80), and in that said first translation means comprise elastic means (90) for automatically translating said tubular jacket (50) in said first translation direction when said at least one first engagement surface (61) of said first fixing station (60) is released from said at least one second rocker arm (80).

9. A rolling mill according to any one of claims 1 to 8, characterized in that it comprises second translation means for translating the tubular jacket (50) with respect to the drawbar (40) in said second translation direction.

10. The rolling mill according to claim 9, characterized in that said second translation means comprise a second fixed switching station (70), said second fixed switching station (70) delimiting at least one second engagement surface (71), wherein translation of said drawbar (40) along a translation direction parallel to said rolling direction and in a second translation sense opposite to said first translation sense causes said at least one second engagement surface (71) to be engaged by said at least one second rocker arm (80) and causes said at least one second rocker arm (80) to switch from said first position to said second position, and switching of said at least one second rocker arm (80) from said first position to said second position causes said tubular jacket (50) to translate in said second translation sense opposite to said second translation sense, and thereby cause the head (30) to switch between the second engaged configuration and the first released configuration.

11. The rolling mill according to claim 10, characterized in that said second translation means comprise means (72) for switching said at least one second engagement surface (71) of said second fixing station (70) to a release position by said at least one second rocker arm (80), and in that the action of said elastic means (90) causes said tubular jacket (50) to automatically translate in said first translation direction when said at least one second engagement surface (71) of said second fixing station (70) is released from said at least one second rocker arm (80).

Background

The production of seamless tubular elements by rolling a blank fitted on a mandrel is known in the prior art. In practice, according to the prior art, the tubular element is obtained from a blank fitted on a mandrel by means of forced passage of said blank through a plurality of rolling stands and/or rolling dies arranged in succession along a predetermined direction, wherein each rolling stand or rolling die defines precisely a passage, and wherein the rolling stands and/or rolling dies (arranged in succession along the advancement direction of the mandrel) define passages of progressively decreasing size, and wherein the thickness is reduced and a progressive lengthening of the initial blank is obtained, by the action of the pressure exerted on the blank by the rolling stands and/or dies and the mandrel itself, thus resulting in the shaping of the tube or tubular element.

For example, in the case of rolling stands, the use of rolling stands is known, which comprise a plurality of rolls (at least two), for example idle rolls but also motorized rolls, arranged one with respect to the other and having a variable number (for example three), according to requirements and/or to the situation, so as to define the above-mentioned forced passage, the dimensions of which are defined by the size, shape and mutual arrangement of the rolls in the respective rolling stand.

Instead, the blanks are obtained from a "billet" according to a method that varies according to requirements and/or conditions.

According to a first method, a cup-shaped blank, i.e. a cylindrical inner cavity with a blind end at one end, is made by means of a press, for example of the vertical type, by means of which a punch is pushed into an initial billet (or block) suitably heated to form said cylindrical blind cavity.

Rolling a blank with a (cup-shaped) blind cavity obviously means that it is necessary to separate the tube, now formed in practice, from the mandrel itself at the exit of the rolling mill stand, and also to cut the end (bottom) from the mother tube before the tube is sent to the (possible) next working cycle, in particular to the deformation cycle.

In contrast, according to the second method described above, the blank is again obtained from an initial billet (or billet), but in this case a tubular blank having a substantially cylindrical through-going, and therefore not a blind cavity, is formed by means of a transverse piercing process.

Rolling a non-blind tubular blank naturally offers the advantage of improving the use of the starting material (thereby avoiding the waste of cutting the bottom), but requires that the blank, once fitted onto the mandrel, is crimped onto the mandrel in the region of its front end, in order to avoid said portion of the blank slipping on the mandrel during rolling.

However, regardless of the type of blank used (cup-shaped with blind cavities or tubular with through cavities), according to the current rolling techniques and/or methods, the blank fitted on the mandrel is conveyed through the rolling mill stand and/or the die by the thrust exerted on the mandrel.

For this purpose, in particular, a push rod is used which, by pushing, engages precisely the end portion of the mandrel opposite to the end portion on which the blank is fitted.

The rolling technique according to the prior art, based on moving the mandrel (and therefore conveying the blank) by pushing exerted on the mandrel itself, presents various drawbacks and/or drawbacks.

Firstly, it is required to use a push rod of a length at least slightly greater than that of the mandrel itself; for example, to produce a pipe having a length of about 21m to 21.5m, the total length of the mandrel and the push rod exceeds 45m, with significant dimensional problems. Furthermore, the spindle-push rod assembly, when compressed and therefore behaves as a very elongated rod, particularly during pushing of the spindle by means of the rod, is inherently unstable in its behaviour and therefore requires the provision of substantial restraining means and/or safety means. For example, a series of constraining guides is generally used, having appropriately shaped sliding tracks dimensioned to minimize the space of movement of the two spindles of the push rod during the working stroke. Such guides are also subjected to considerable forces, impacts and vibrations during rolling, wherein the use of the guides requires the provision of a fixing system of the guides themselves, wherein the length of the guides may exceed 40m, and wherein the use of the guides implies very high maintenance costs resulting from the need to replace worn linear rails. Moreover, in the case of systems allowing the use of spindles of different diameters, additional management costs must be considered due to the need to act on the constraining guides and/or to replace said linear rails with linear rails of suitable diameter for each replacement of a spindle (this operation is rather complex and of long duration).

Finally, the pusher-bar system loaded with a pointed tip (typically a pusher-type rolling mill as described previously) involves an inevitable torsional movement of the mandrel between the rolling stands and/or the rolling dies, which defines its constraints, with the inevitable consequence that undesirable lateral loads on the rolling stands and/or dies, and therefore the dimensional tolerances of the tubes, are inevitably worsened, or in the case of excessive thrusts or transverse loads, there is also the risk of damaging or scrapping the rolling stands.

The pushed spindle is also potentially dangerous if it jams, for example by colliding with the rolling stand and/or exits laterally from the constraints represented by the rolling stand itself.

The main object of the present invention is therefore to overcome or at least minimize the drawbacks outlined above and found in the push rolling mills of the prior art.

In particular, a first object of the present invention is to provide a solution for rolling tubular elements, in particular seamless tubular elements, from a tubular blank having a through-cylindrical inner cavity (hereinafter also simply referred to as "perforation"), which allows to overcome or at least minimize the problems outlined above and found in the pusher-type rolling mills according to the prior art.

In particular, it is an object of the present invention to provide a rolling mill of the aforementioned type which is characterized by low installation costs, also low and/or controlled maintenance costs, easy or at least simplified use, and which allows to reduce the risks both for the operator and for damaging the rolling mill stands and/or the dies, and which is also characterized by improved versatility, since it can be used without substantial modifications (for example, replacement of the sliding rails, if provided) to roll tubular elements of different diameters using spindles of different respective diameters.

Description of the invention

The present invention is based on the general consideration according to which the drawbacks found in rolling mills of the pusher type according to the prior art and briefly outlined above can be overcome by a solution that provides the movement of the mandrel (and of the hollow blank fitted thereon by feeding) by means of traction on the mandrel itself.

In this way, twisting of the push rod-spindle assembly and the resulting lateral thrust on the rolling stand and/or the rolling die are avoided or at least limited.

Finally, by avoiding the use of push rods, it is possible to control the depth of the underlying foundation and to avoid the use of guides and/or corresponding sliding rails, which are essential in the case of a push-bed rolling mill.

In view of the above-mentioned drawbacks encountered with rolling mills according to the prior art and with respect to the purposes of the present invention, according to one embodiment, the present invention relates to a rolling mill for rolling tubes, in particular seamless tubes, comprising a rolling section having a plurality of rolling stands and/or rolling dies arranged in succession to define a rolling axis, said rolling mill further comprising movement means for moving along said rolling axis and in succession through said rolling stands or rolling dies a mandrel and a tubular blank fitted on an end portion of said mandrel; wherein the moving device is configured to move the mandrel and the blank along the rolling axis and continuously through the roll stand or rolling die by a traction force on the mandrel.

According to one embodiment, the movement means comprise an engagement operating head which is switchable between a first release configuration and a second engagement configuration and is adapted to engage and selectively release a handle integral with the end portion of the mandrel, wherein when the operating head is in the second engagement configuration and engaged on the handle, movement of the engagement operating head in a direction parallel to the rolling axis causes translation of the mandrel and the blank along the rolling direction and continuously through the rolling stand or rolling die.

According to one embodiment, the engagement operating head comprises at least one first rocker arm adapted to be switched to pivot between a first position and a second position, and wherein switching of the at least one rocker arm from the first position to the second position causes the operating head to switch from the first release configuration to the second engagement configuration, while switching of the at least one rocker arm from the second position to the first position causes the operating head to switch from the second engagement configuration to the first release configuration.

According to one embodiment, the rolling mill comprises switching means for selectively switching said at least one rocker arm between said first position and said second position.

According to one embodiment, said at least one first rocker arm is hinged on a point integral with a drawbar of said moving device, wherein said drawbar is at least partially housed in a tubular sheath which can translate with respect to said rod, and wherein translation of said tubular sheath with respect to said drawbar in a first translation direction causes said at least one first rocker arm to switch from said first position to said second position, while translation of said tubular sheath with respect to said rod in a second translation direction opposite to said first translation direction causes said at least one rocker arm to switch from said second position to said first position.

According to one embodiment, the rolling mill comprises first translation means for translating the tubular jacket in the first translation direction with respect to the drawbar.

According to one embodiment, the first translation means comprise a first fixed switching station defining at least one first engagement surface and at least one second rocker arm hinged on a point integral with said drawbar, wherein translation of said drawbar along and in a translation direction parallel to said rolling direction causes said at least one first engagement surface to be engaged by said at least one second rocker arm, and said at least one second rocker arm switches from a first position to a second position, and wherein switching of said at least one second rocker arm from said first position to said second position causes said tubular jacket to translate in said second translation direction.

According to one embodiment, said first translation means comprise means for switching said at least one first engagement surface of said first fixing station into a release position by said at least one second rocker arm, wherein said first translation means comprise elastic means for automatically translating said tubular sheath in said first translation direction, wherein said at least one first engagement surface of said first fixing station is released from said at least one second rocker arm.

According to one embodiment, said rolling mill comprises second translation means for translating said tubular jacket with respect to said drawbar in said second translation direction.

According to one embodiment, said second translation means comprise a second fixed switching station defining at least one second engagement surface, wherein translation of said drawbar along a translation direction parallel to said rolling direction and in a second translation direction opposite to said first translation direction causes said at least one second engagement surface to be engaged by said at least one second rocker arm and causes said at least one second rocker arm to switch from said first position to said second position, and wherein switching of said at least one second rocker arm from said first position to said second position causes said tubular jacket to translate in said second translation direction.

According to one embodiment, said second translation means comprise means for switching said at least one second engagement surface of said second fixing station into a release position by means of said at least one second rocker arm, wherein the action of said elastic means causes automatic translation of said tubular sheath in said first translation direction when said at least one second engagement surface of said second fixing station is released from said at least one second rocker arm.

Further embodiments of the rolling mill according to the invention are defined in the claims.

The invention also relates to a rolling method carried out by a rolling mill according to any one of the embodiments outlined above.