US1989059A - Tube forming roll - Google Patents

Description

Jan. 22, 1935. R. c. F. K-URTZE 1,989,059

TUBE FORMING ROLL Original Filed Sept. 1, 1931 2 Sheets-Shae 1 Mal a C Jan. 22, 1935. R. or. KURTZE 1,939,059

TUBE FORMING ROLL Original Filed Sept. 1. 1931 2 Sheets-Sheet 2 INVENTOR Patented Jan. 22, 1935 UNITED STATES PATENT OFFICE Morgan, administrator of said Kurtze, deceased, assignor to Republic Steel Corporation, Youngstown, Ohio, a corporation of New Jersey Application September 1, 1931, Serial No. 580,841 Renewed June 12, 1934 'IClaims.

This invention relates to improvements in the structure of roll passes for forming a metal tube by bending a flat strip of metal longitudinally and progressively to cylindrical shape.

A tube is formed by moving a flat strip of metal longitudinally through a series of shaping passes for bending the edges of the strip together to formthe seam of a continuous cylinder. These passes have comprised rolls with faces opposed to each other and shaped to appropriate contour for bending the strip. The passes are adjusted to separate the opposed shaping faces commensurately with the thickness and position of the metal blank, and the rolls are driven to advance the strip by frictional contact.

-In operation, one difficulty is that strips tend to be twisted out of alignment in being propelled through the passes, so that the seam is skewed from a straight line. This turning of the walls of the blank consumes considerable energy and leaves the metal in undesirable conditions of strain that weaken the tube both mechanically and in resistance to corrosion. Twisting of the blank also makes it diilicult subsequently to feed the tube properly through a welding machine.

With tubes of large diameter or of heavy wall, increasing numbers of factors contribute to faulty alignment of the seam and of the side walls. Irregularities in the thickness of the blank become more important, greater pressures are required to bend the greater mass of metal, and the faces of the rolls become distorted more easily. In general, the maintenance of proper alignment in a metal blank during bending becomes a more pronounced problem with increase in wall thickness or in diameter of the tube being formed.

It is an object of this invention to improve the structure of roll passes so as to decrease skewing of an elongate blank during bending to tubular form. A further object is to provide roll passes that contain shaping elements appropriate for bending even heavy wall or wide strips to continuous cylindrical form, and that retain the shaping elements in suitable alignment despite con-- siderable usage.

According to this invention, these objects are accomplished in part by providing roll passes with arcuate forming rolls having the middle portion of the concave bending faces recessed out of the general contour of the pass, the passes containing an opposed convex roll to press against only the edge portions of the concave shaping face. One or more of the rolls in a pass preferably is mounted yieldably, so that during operation its ends may adjust themselves to any unsymmetrical variations in thickness of a strip. A further element of this invention that contributes to maintenance of alignment is the provision of pairs of inner shaping rollers supported to press against each other and to press against the inner side walls in cooperation with corresponding exterior forming rolls. Preferably these inner rollers are supported on spindles that extend through the seam space at the more nearly cylindrical portions of the blank.

Figs. 1 to 9 respectively are elevations of pinch rolls and of eight subsequent shaping roll passes, constituting a progressive series; Figs. 10 and 11 are elevations of finishing passes that perfect the circular shape of the formed tube and, particularly, fix the arcuate contour of the seam area in permanent form; Fig. 12 is a vertical section through a pass to show the yieldable mounting of a roll housing to permit a pass to adjust itself to variations in the position of the surfaces of a metal blank duringits passage; and Fig. 13 is a horizontal section of a yieldably mounted roll, as section AA of Fig. 12.

Referring more particularly to the drawings, in

which representative elements are numbered, it is evident that each pass comprises cooperating rolls mounted with shaping faces opposed to each other, as rolls 1 and 2 of Fig. 2 and rolls 3, 4 and -5, 6 of Fig. 6, for example. Each pass contains one or more forming rolls to provide a concave shaping face having its middle portion eliminated from the general contour of the pass so that a. metal blank B that conforms generally to the pass bridges over the middle of the forming face. For example, in Fig. 2 there is a forming roll 2 with its middle portion cut away peripherally, and in Fig. 6 there are two lateral forming rolls 3, 4 spaced from each othersymmetrically so that the middle of the pass is free from contact with the blank. With this arrangement, the rolls hold a blank under pressure at the sides, but they afford no central pivot should the pressures on the margins of the moving blank become unequal, as they do when the sheet varies in thickness or contains irregularities of surface. Either margin that may be held under increased prmsure tends to be retarded in its passage, while the opposite edge under the less pressure tends to advance relatively faster. Where the middle of a blank is subjected to pressure in a pass the strip thus tends to pivot somewhat about the middle of the pass and to stretch the metal of the more rapidly advancing edge. The unequal lengthening effect is cumulative and in the aggregate tends to twist the seam considerably from a straight line. But by eliminating the middle of the forming face of a plurality of passes, the edges of a blank are caused to travel more nearly at equal rates despite any relative differences of pressure on the margins of the blank, and thus the seam is kept in better alignment. There may be supporting faces for the middle of the strip, but they apply no shaping pressure that would tend to pivot the moving blank.

In order that the shaping rolls may adapt,

themselves to surface irregularities of a blank, one or more of the rolls of each pass is mounted yieldably so that the edges of the pass adjust themselves to counteract inequalities of pressure. This is indicated in Figs. 2 and 8, with suitable structure illustrated more in detail in Figs. 12 and 13.

In Fig. 12 opposed shaping rolls 1 and 2 are mounted in a frame 33. The lower roll 2 is shown journalled in a stationary housing, but the upper roll 1 is journalled in a housing 7, the upper side of which is seated pivotally against avertically adjustable central pin 8 carried by the frame. The lower sides of the housing are supported on springs 9 and 10 that serve to press the housing upwardly against the pivot pin 8. with such arrangement any relative increase of one side of the blank B results in lifting that side of the yieldable shaping roll 1, and thus equalizing the pressures at the edges of the pass.

Fig. 13, a cross section of the upper part of housing 7, along the line AAof Fig. 12, shows a slight spacing of housing 7 from frame 33 along a narrow but long area of contact to permit the required pivotal play. Along their sides, however, housing '1 and frame 33 fit closely in order to prevent any misalignment of the roll, toward the front or back.

In passes having exterior shaping rolls mounted vertically at opposite sides of the pass, as rolls 11 and 12 of Fig. 8, at least one of the rolls is journalled in a vertically disposed arm, as 13, that is pivotally mounted to permit equalization of pressure at the edges of the pass.

Further elements of this invention appear in the mounting of convexrollers within the blank at the later passes of the series. Such rollers afford lateral pressure outwardly in cooperation with the external rolls for completing the cylindrical shape of the blank. Since it has been difficult because of lack of space to mount rolls inside the blank where the seam edges converge and since a supporting arm of appreciable length is disadvantageous, pairs of mutually-contacting inner rolls 1;! and 15 are mounted on bifurcated spindles 16 that extend through the narrow space of the closing-seam, as illustrated by Figs. '7 and 8 or by rolls 5, 6 of Fig. 6. These rollers are not driven but rotate by their contact with the moving blank. As shown, the contour of their faces is appropriate to their position in the series of passes. They afford the outward thrust necessary to bend the considerable mass of metal in heavy-wall material to the shape of the pass, and with any blank they provide areas of maximum pressure that are balanced at opposite sides of the blank to prevent one edge creeping ahead of the other.

These inner rollers are guided by light spindles, but with their faces in contact with each other the burden on the spindles is negligible as they transmit side thrust between their corresponding exterior rolls. The considerable pressures necessary for bending the side walls of heavy tubes, must be counteracted, however, or

they would crush and destroy the normal contour of the convex faces of the inner rolls and thus lead to unequal movement of the walls of vthe blank and to aggravation of skewing of the seam edges. To prevent this crushing of the convex roller faces, the faces are flattened peripherally at the middle. This avoids point contact, the flattened contact faces thus distributing and decreasing the unit pressure of their mutual contact. In this way the period of usefulness of these inner rolls is increased, and they are better able to maintain proper alignment of the side walls of a blank.

, Fig. 9 illustrates outer rolls and the mounting of inner rollers near the end of the series of passes, where the problem becomes more diflicult to bring the seam area to proper alignment. Here is illustrated a pass in which two external rolls 17 and 18 applying pressure near the seam, cooperate with a vertically disposed pair of inner rolls 19 and 20. Since the seam is substantially closed, the inner rolls mounting on a vertical spindle becomes impossible, and they are set loosely within the tube, contacting with each other and with the walls of the tube, and held in place by plates 21 and 22 at their side. These plates extend in the tube as an arm, but they extend only a relatively short distance and sustain practically no load. Such resultant thrust as is downward from outer rolls 1'7 and 18 may now be borne by the tubing itself or by a simple supporting roller under it.

Following the series of shaping rolls proper, is what may be termed a settingpass, shown in Fig. 10. The pass of Fig. 10 consists of three rolls 23, 24, 25. Roll 23 supports the'tubing and rolls 24 and 25 are mounted separately to apply pressure against opposite sides of the seam for permanently setting the metal close to the seam to the contour to which it has been brought by the shaping passes. This arrangement is useful oecause of the considerable pressure necessary to overcome the existing leverage of the metal at the edges and to bring the extreme edge area along the seam from flat to circular form. Where has been unsatisfactory in practical operations to design roll bearings and faces adequate for the purpose, but a pass of three cooperating rolls to terminate the shaping passes permits a satisfactory practical arrangement to accomplish the final setting of the edges in a dependable manner.

Following this finishing pass for setting the edges is a final shape adjusting pass of three rolls 26, 2'7, 28, Fig. 11, for perfecting the circular contour of the walls of the tube.. In this pass two rolls are mounted for supporting the tube having arcuate faces that contact extensively. with the tube walls opposite the'seam. The third roll likewise is arcuate and is mounted across the seam. With this mounting it is possible to arrange heavy. bearings so that these rolls between them can apply considerable pressure over substantially the entire wall of the tube and adjust irregularities in its contour.

According to the provisions of the patent statutes, I have explained the principle and mode of operation of my invention and have illustrated and described what I now considerto represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically illustrated and described.

I claim: 1. A tube-forming pass having generally parallel arcuate shaping faces with the middle of the pass faces removed from contact with a blank lying in the general contour of the pass, said pass comprising opposed concave shaping rolls mounted symmetrically at the sides of the pass, and generally convex backing rolls opposed to said concave rolls and cooperating therewith to shape the edge portions of a blank. 2. A tube-forming pass having generally parallel, opposed shaping faces with the middle portion of the pass removed from contact with a tube blank lying in the general pass contour, and comprising lateral shaping faces at opposite sides of the pass mounted rockably relatively to each other for adaptation to irregularities of surface alignment in a blank moving through the pass. 3. A tube-forming mill comprising a series of shaping passes adapted to bend a strip of metal progressively to cylindrical form and containing concave rolls having shaping faces at opposite sides of a pass to leave the middle portion of the pass free from contact with a tube blank lying in its general contour, and inner shaping rollers parallel to the lateral roll faces, the concave rolls at the sides of the pass being mounted rockably relatively to each other for adaptation to irregularities of surface alignment in a moving blank. 4. In a tube-forming mill, a shaping pass comprising a frame, a shaping face mounted in fixed position in said frame, a housing rockably mounted in said frame, a shaping roll journalled in said housing for cooperation with said shaping face, a pivot bearing mounted in fixed position above said housing, and springs acting between the sides of said housing and frame resiliently urging the housing into contact with said bearing, whereby variations in thickness transversely of tube blanks supplied to the mill cause said housing and roll to rock about said fixed pivot in the plane of the longitudinal axis of the roll and thereby to equalize the pressure applied by the pass.

5. In a tube-forming mill, a shaping pass comprising a frame, a concave roll journalled in fixed position in said frame, a housing rockably mounted in said frame, a convex shaping roll journalled in said housing for cooperation with said concave roll, a pivot bearing mounted in fixed unyielding position in said frame above said housing, and springs acting between the sides of said housing and said frame resiliently urging the housing into contact with said bearing, whereby variations in thickness transversely of tube blanks supplied to the mill cause said housing and convex roll to rock about said fixed pivot in the plane of the longitudinal axis of the roll and thereby to equalize the pressure applied by the pass.

6. In a tube-forming mill, a shaping pass comprising a frame, opposed cooperating shaping rolls, one of said rolls being journalled in said frame in fixed position, and the other of said rolls being journalled for rocking in the plane of its longitudinal axis about a fixed unyielding pivot positioned centrally of the roll whereby the roll rocks in response to variations in thickness transversely of blanks supplied to the mill and thereby equalizes roll pressure transversely of the blank.

7. A tube-forming pass comprising rolls mounted to form lateral shaping faces at opposite exterior sides of the pass and rockable with respect to each other for adaptation to differences of surface alignment in a tube moving through the pass, a pairof inner rollers forming interior shaping faces supported within the blank to contact with each other and with the interior of the blank opposite said exterior rolls to counteract side thrust thereof, and spindles mounted within the blank carrying said inner rollers.

REIMAR C. F. KURTZE.

Images