US1978422A - Method and apparatus for the manufacture of tubes - Google Patents

Description

F. E. FIEGER Oct. 30, 1934.

METHOD AND APPARATUS FOR THE MANUFACTURE OF TUBES Filed March 10. 1931 2 Sheets-Sheet l FMEF QZZZSL AM Oct. 30, 1934. FIEGER 1,978,422

METHOD AND APPARATUS FOR THE MANUFACTURE OF TUBES Filed March 10. 1933. 2 Sheets-Sheet 2 ill;

INVENTOR PM E'FQ'KI Patented a. 30, 1934 UNITED STATES PATENT OFFICE rm'rnon AND APPARATUS Foa run MANUFACTURE or runes Application March 10, 1931, Serial No. 521,486

paratus for the manufacture of tubes, the word "tubes being used as a word of broad definition and not limitation, and being intended to designate tubular products generally regardless of their mercantile classification.

There is a great demand for seamless steel tubes, which demand has heretofore been supplied by a process of manufacture involving piercing of a solid billet. followed by rolling on an automatic return mill, or plug mill as it is sometimes termed. The piercing is effected in a mill of the Mannesmann or Stiefel type wherein a pair of rolls simultaneously rotates and transversely compresses the steel billet while feeding it forward over a piercing point. In order to get satisfactory yields it is necessary to employ a high grade'of steel, as otherwise there will be too great a loss in the piercing mill. The quality of go the steel tobe used is determined, not by the requirements of the final product, but by the necessities of manufacture. The piercing opera-.

tion requires careful and constant supervision and the expenditure of high power. Difficulty is frequently had in obtaining concentricity.

I provide for forming a tube blank by the push-bench process and supplying such blank to an automatic return mill for further elongation and reduction of wall thickness. According to the push-bench process of manufacture, a heated billet of relatively short length is placed in a press and punched for a major portion of its length so as to form a hollow body closed at one end. This body is placed over the end of a-mandrel and pushed through a ring bench carrying dies of successively decreasing diameter. The dies reduce the diameter of the blank and elongateit over the mandrel. The common practice is to form the tube completely on the push bench except for small sizes where, as in the case of the piercing and plug mill method, resort is had to a reducing mill for elongating and decreasing the diameter of a formed tube.

I have found, however, that material advantages may be derived from combining the push bench process with the automatic return'mill, and that high quality tubes may be thereby produced at relatively low cost. The push bench permits of using a quality of'steel which, while 5 entirely satisfactory in the finished product,

need not be so carefully supervised in its manufacture as steel intended for the piercing process. Material economies are thereby effected at the outset. The trend of consumers is toward long length tubes, and where the tube is produced 9 Claims. (01. za-sa) This invention relates to a method and apsolely by the push-bench process it is necessary to employ a mandrel longer than the longest length of finished tube desired (barring those sizes which are produced-in the reducing mill). The amount of reduction per die in the push bench is limited, for the force exerted by the die must not be so great that the endof the mandrel will punch its way through the closed end of the blank. This tendency of the mandrel also limits the number of dies which may be active at any one time. For example, in the earlier and heavier reductions it may be considered advisable to have the blank in only two dies at any one time. Consequently, if the tube is to be reduced to final size in the push bench it requires an installation of very great length, necessitating a large captial investment. Moreover, this extreme length renders more diflicult the problem of maintaining the tube truly concentric, since the mandrel derives its entire support from the connection to the push bar at the rear end of the mandrel and, radially, only through the hot metal which is being worked.

If, on the contrary, the push bench is relied on only to form a tube blank of relatively heavy wall thickness and limited length, the total length of the push bench may be greatly reduced and the shorter mandrel bars will be stifier, resulting in more concentric tubes. There will be less heat loss and a faster cycle of operations is possible. Material economies in power may also be effected.

In the accompanying drawings illustrating a present preferred embodiment of my invention,

Figure 1 is a plan view of an installation for the manufacture oftubes,'and

Figure 2 is a view to enlarged scale of a portion of Figure 1.

Figure 1 illustrates a furnace 2 having a pusher 3 whereby square billets B are fed through the furnace and brought up tov heat. Side doors 4 are provided so that after the billets reach the delivery end of the furnace they may be engaged by tongs and turned over so as to separate the leading billets in the train from one another, thereby equalizing the heat. The heated billets are discharged through doors -5 to transfer cars 6 leading to the press '7. The press has a cylindrical die 8 which receives the square billet, and a circular punch 9 is forced into it so as to produce a bottle or tube blank. This blank is ejected from the die 8 and carried by a swinging arm 10 to a position indicated at C on the push bench 11. A mandrel 12 is inserted in the throttle and the mandrel is then pushed forward to re- Q AQQ the tube. It is supported at its rear end on 1 a push bar 13 extending forwardly from a rack 14 driven by a motor 15. When the motor is actuated to drive the mandrel to the right, as viewed in Figure 1, the bottle is pushed through a series of dies 16 successively decreasing in diameter, so that when the mandrel has been pushed completely through the dies, a tube blank T has been formed thereon from the bottle. The mandrel is disconnected from the push bar 13 and lies on a roll table 17. It is fed forward through a reeler 18 which loosens the tube on the mandrel and delivers it to table rollers 19. The tube and mandrel are then fed over skids 20 to table rollers 21 which hold the mandrel in alinement with a stripping die 22. The rear end of the mandrel is fed through the stripping die by actuating the table rollers 21. This end is grasped by a tongs 23 connected to a chain 24. The chain is pulled to the left by a motor 25, thus drawing the mandrel out of the tube blank. The tube blank is then carried away from the stripping die 22 by means of the table rollers 21 and kicked off onto skids 26 over which it rolls until it is received by table rollers 27.

The stripped mandrel, after being released by the stripping tongs 23, may be carried by table rollers 28 to skids 29 from which it is fed back to the push bench 11, or it may be carried over transfer skids 30 to table rollers 31 and thence back to the skids 29 by reason of a reheating furnace 32 which equalizes the temperature of the mandrel. This feature is more fully described and claimed in a copending application-0f Carl W. Littler, Serial No. 513,307, filed February 4, 1931. After the tubereaches the table rollers 27 it is fed forward so that its ends may be cut off by a hot saw 33. After the ends have been out 01f the tube blank is lying on table rollers 34 from which kick-offs 35 transfer it to rollers 36. A pusher 37 then feeds the tube blank to a reheating furnace 38 from which reheated tubes are delivered by. reason of a pusher 39 (see Figure 1) to rollers 40. If desired, the tubes may be fed directly from the rollers 36 to the rollers 40 over skids 41.

A kick-off 42 transfers the tube blank to the trough 43 of an automatic return mill indicated generally by the reference character 44. This mill comprises driven rolls 45 supplied with power from a motor 46 (see Figure 1), a pusher 46a for moving the tube blank into the grip of the rolls, a bar 4'7 extending from a back-stop 48 and adapted to support plugs P over which the tube is rolled, and return rolls 49. In operation, the rolls 45 feed the tube blank, once it has been moved into their grip, and roll it over the plug P, reducing its wall thickness and elongating the blank. When the tube has been fed all the way through the rolls 45 are separated and the return rolls are automatically rendered effective for feeding the tube back to the trough 43. The upper return roll 49 is fixed in position, while the lower roll is automatically moved upwardly so'as to frictionally engage the tube after the reducing rolls 45 have been separated. The return rolls are driven by a motor 50. The construction and operation of the plug mill are well known and require no extended description. A workman puts a fresh plug on the end of the bar 47 after each reducing pass and the tube blank is turned through 90. Several passes are given and the tube is thereby reduced and elongated. When the plug rolling has been completed the tube is lifted by kick-offs 51 onto skids 52 over which it travels to a roll table 53. If desired it may be lifted from the roll table 53 by kick-offs 54 to skids 55 leading to a roll table 56. The roll tables 53 and 56 are in alinement with reelers 57 which roll the tubes helically over plugs held by freely rotating mandrel bars 58. The mandrel bars 58 are held against endwise movement during the reeling of the tube, but after the tube has cleared the reeler the mandrel bar is withdrawn by a mechanism indicated generally at 59. The rolling operation serves to reduce any inaccuracies of wall thickness and to smooth and round the tube. From the reelers the tubes pass to a roll table 60 and thence to a sizing mill 61 wherein the tube is brought down to the precise outside diameter required. From the sizing mill the tubes pass to a cooling rack 62.

I have illustrated and described a present preferred embodiment of my invention but it will be understood that this is by way of illustration only and that the invention may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. In the method of making tubes, the steps consisting in subjecting a hollow heated metal body to the action of successive reducing dies, thereby forming a tube blank, and elongating the blank and thinning its wall by rolling it over a plug while maintaining the plug stationary in the direction of advance of the blank.

2. In the method of making tubes, the steps consisting in placing on the end of a mandrel a hollow heated metal body having one end closed, and subjecting it'to the action of successive reducing dies, thereby elongating the metal body over the mandrel and forming a tube blank, and further elongating the blank and thinning its wall by rolling and rotating it over a plug.

3. In the method of making tubes, the steps consisting in subjecting a hollow heated metal body to the action of successive reducing dies, thereby forming a tube blank, and elongating the blank and thinning its wall by a plurality of plug rollings.

4. In the method of making tubes, the steps consisting in placing on the end of a mandrel a hollow heated metal body having one end closed and subjecting it to the action of successive reducing dies, thereby elongating the metal body over the mandrel and forming a tube blank, removing the blank from the mandrel, opening the closed end, and further elongating the blank by subjecting it to a plug rolling.

5. In the method of making tubes, the steps consisting in placing on the end of a mandrel a hollow heated metal body and subjecting it to the action of successive reducing dies, thereby forming a tube blank, reheating the blank, and further elongating it and thinning its wall by rolling it over a plug.

6. In the method of making tubes, the steps consisting in placing on the end of a mandrel a hollow heated metal body and subjecting it to the action of successive reducing dies, thereby forming a tube blank, and before the blank cools further elongating it and thirming its wall by rolling it over a plug while maintaining the plug stationary in the direction of advance of the blank.

7. Apparatus for the manufacture of tubes comprising a push bench, a mill of the type commonly known as a plug mill which comprises a plug positioned substantially stationarily in the direction of advance of blanks therethrough,

9. Apparatus for the manufacture of tubescomprising a push bench, a mill of the type commonly known as a plug mill which comprises .a plug positioned substantially stationarily in the direction of advance of blanks therethrough for reducing blanks formed on the push bench, and means for heating such blanks.

FREDERICK E. FIEGER.

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