Patent Publication Number: US-6666060-B2

Title: Roller head for a planetary rolling mill

Description:
The present invention relates to a roller head. 
     Roller heads according to the object of the invention are used in planetary rolling arrangements, where the employed rolling members are mainly conical rollers. Typical prior art roller heads are introduced among others in the following patent publications: U.S. Pat. Nos. 3,718,020, 3,735,617 and 4,587,820. In certain practical applications of the roller heads according to the present invention, it is very important that the roller can be adjusted accurately in the axial direction. In known roller adjusting methods, a drawback is that said methods are very complicated, and/or that the axial adjustment of the roller is inaccurate owing to the employed coupling member arrangements of the adjusting apparatus. Prior art solutions have mainly utilized cogged coupling members for coupling the adjusting axis. Owing to the coupling arrangements of known solutions, the axial adjustment has become stepped. This has lead to a situation where the minimum quantity of the axially directed motional shift has been dependent on the cogging of the coupling member. Moreover, in prior art solutions, it has been troublesome to accurately measure the adjustment to be performed. 
     The object of the present invention is to achieve a completely new type of arrangement for enabling an advanced and more accurate method for performing the axial adjustment of a roller head. Another object of the invention is to achieve a roller head that enables the measurement of the axial adjustment in an easy and accurate manner. 
     The invention is characterized by what is stated in the accompanying claims. 
     The roller head according to the invention has several remarkable advantages. The adjusting arrangement according to the invention enables an extremely accurate and stepless axial adjustment. When applying a stepless locking of the adjusting shaft, there is achieved a remarkably higher axial distance and centering accuracy for the rollers than in the prior art arrangements. By employing an expansible sleeve member as the locking member, there is achieved an extremely feasible solution for a locking member. By employing a pressure-operated sleeve member and particularly by employing a liquid as the pressure medium, said liquid being for instance hydraulic oil, there is achieved a suitable arrangement to be used in connection with the roller head. This solution enables a situation where the locking member constitutes a uniform piece with the adjusting member, or a situation where the locking member is a separate sleeve member between the adjusting shaft and the outer shaft. 
    
    
     The invention is explained in more detail below, with reference to the appended drawings, where 
     FIG. 1 illustrates a cross-section of a roller head according to the invention, and 
     FIG. 2 illustrates an enlarged detail A of FIG.  1 . 
    
    
     The roller head illustrated in the drawings is a roller head used in the so-called PSW rolling mill (Planeten Schrägwalzwerk, planetary skew-rolling mill). Typically a PSW rolling mill includes three roller heads. The roller head  1  is arranged turnably in the rotor (not illustrated). 
     The roller head  1  according to the invention comprises a housing  8 , inside which housing there is rotatably arranged a hollow outer shaft  5  and means  2 ,  3 ,  4  for rotating said outer shaft, as well as a center or inner shaft  6  arranged inside said outer shaft, in a manner that transmits the rotary motion of said outer shaft; said center shaft  6  is movable in the axial direction and lockable in the axial direction, and it is also provided with a roller  7 . In the operating shaft  2  of the roller head, there is arranged a drive wheel  3 , the rotary motion whereof is transmitted by means of a counterwheel  4  to the hollow outer shaft  5  of the roller head. The outer shaft  5  is arranged rotatably inside the housing  8  of the roller head  1  by intermediation of bearing members  9 ,  10 ,  11 . The outer shaft  5  of the roller head is rotatably arranged in the roller head housing, at least by two radial-thrust bearings  9 ,  11 , and by an axial bearing  10  provided therebetween. Inside the outer shaft  5 , there is arranged a center shaft  6  movably in the axial direction. On the inner surface of the outer shaft  5 , there are typically formed for example cogged coupling members  12 ,  13 , in which case in the center shaft  6 , there are arranged counterparts that prevent the center shaft  6  from rotating with respect to the outer shaft  5 , but allow the center shaft to move in the axial direction. The roller  7  is arranged in the center shaft  6 . The roller head is characterized by an adjusting shaft  16 , which is arranged rotatably at that head of the outer shaft  5  that is located at the opposite end with respect to the roller  7 , said adjusting shaft being essentially locked in the axial direction and comprising a counterpart  17  for the threaded section  15  provided in the center shaft  6 ; said adjusting shaft  16  includes a locking member  18 , which in the locking position forms a friction coupling at least between the adjusting shaft  16  and the outer shaft  5 . At that end of the center shaft  6  that is located on the opposite side with respect to the roller  7 , there is arranged a bore  14  with threadings  15  made in the side wall thereof. At that end of the roller head that is on the opposite side with respect to the roller  7 , there is arranged an adjusting shaft  16 , comprising a counterpart  17  for the threaded section  15  of the center shaft  6 . The position of the center shaft  6  in the axial direction can be adjusted by turning the adjusting shaft  16 . As a result, the position of the center shaft  6  is changed by a distance determined by the thread of the threaded section and the counterpart, depending on the amount of the rotary motion of the adjusting shaft. Typically the threads of the threaded section and the counterpart are extremely precise, for instance so-called trapezoidal threads. Typically the threaded section  15  of the center shaft is arranged in a bore  14  made in the center shaft, in which case the counterpart  17  of the adjusting ante shaft is a screw member. The adjusting shaft  16  comprises a locking member, such as a sleeve member  18 , whereby the adjusting shaft can be steplessly locked in the outer shaft  5 . The locking member  18  is typically an expansible, pressure-operated sleeve member. In a preferred embodiment, the locking member  18  is a hydraulically operated sleeve member. In the embodiment according to the drawings, the locking member  18  constitutes a uniform piece with the adjusting shaft  16 . The locking member can also be a separate sleeve member located between the outer shaft  5  and the adjusting shaft  16 . By means of the sleeve member  18 , for instance the winding of the adjusting shaft is prevented, and thus also the center shaft  6  is locked in the axially adjusted position. Typically the adjusting shaft  16  comprises members, such as shoulders  19 ,  20 , in order to prevent it from shifting in the axial direction, at least during the adjusting process. 
     FIG. 2 shows part of the roller head in cross-section. FIG. 2 also shows a typical embodiment of the structure of the locking member  18 . The locking member illustrated in the drawing is a so-called hydraulically operated sleeve member. There is arranged a fluid channel system  21 ,  22 ,  23  with some hydraulic fluid provided therein. When the liquid pressure in the channel system is raised, the sleeve  18  is at least partly expanded in the radial direction and attached, at the outer surface  18 ′, to the countersurface, which in the case according to the invention is the typically cylindrical surface  5 ′ located in the bore of the outer shaft  5 . In the embodiment illustrated in the drawings, in the adjusting shaft  16  there is formed a liquid channel  23 , provided with an adjusting screw  24 , and by turning said screw the liquid pressure is raised or lowered in the channel system  21 ,  22 ,  23  of the sleeve member. In the arrangement according to the invention, the sleeve member  18  can form part of the adjusting shaft  16 , in which case it in the fastening position radially affects the outer shaft  5  located outside said sleeve member, or it can be a separate sleeve member, in which case the sleeve member  18 , by increasing pressure, radially affects the adjusting shaft  16  located inside it, as well as the outer shaft  5  located outside it. 
     The invention is operated so that the adjusting shaft  16  is locked, while the rolling mill center shaft  6  is adjusted at a desired point, to the outer shaft  5  by means of the locking member is, most suitably by a friction coupling, in which case also the center shaft  6  is locked in the axial direction. In the case illustrated in FIG. 2, the expansive sleeve  18  serving as the locking member is pressurized by tightening the adjusting screw  24 , so that the sleeve is expanded and forms a friction coupling. When the center shaft should be adjusted in the axial direction, the adjusting screw  24  is screwed open, in which case the sleeve  18  is contracted and the friction coupling is released, and the adjusting shaft  16  can again be turned. The axial motion of the rolling will center shaft  6  can be created and measured extremely accurately by providing, for the duration of the adjusting process, an installation device  25  coupled to a measuring device  26 . The installation device includes a torsion shaft  27  comprising a counterpart  29  for the driver  28  of the adjusting shaft  16 . The amount of the axial motion of the center shaft is obtained when the size of the rotary motion of the adjusting is measured. Advantageously the measuring device  26  is arranged to directly indicate the amount of the axial motion at a typical accuracy of for instance 0.01 mm. 
     By means of the roller head according to the invention, the axial adjustment is carried out more accurately than in the prior art. By employing an installation device provided with a measuring device, the adjusting process is carried out quickly and precisely.