US3882981A

US3882981A - Silencing means for steel pipe production lines

Info

Publication number: US3882981A
Application number: US253756A
Authority: US
Inventors: Akio Izumidate; Susumu Itoh
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1971-05-17
Filing date: 1972-05-16
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13
Also published as: DE2223797B2; CA960163A; DE2223797A1; DE2223797C3

Abstract

Silencing means for repressing or reducing noise of impact between steel pipes being transferred by means of electromagnets provided between adjacent skid rails such that magnetic circuits are formed by these electromagnets, skid rails and steel pipes being transferred. Magnetic forces set up by the electromagnets acts to cancel the acceleration of steel pipes rolling on the skid rails to reduce the speed of the steel pipes being transferred, thereby reducing the energy of impact between steel pipes for repressing or reducing noise at the time of impact between steel pipes.

Description

Izumidate et a1.

1451 May 13, 1975 1 SILENCING MEANS FOR STEEL PIPE 1,727,163 9/1929 Fehringer et a1, .1 188/164 x NE 1,752,162 3/1930 Fehnnger et all 188/164 X PRODUCTION LI 5 1,859,764 5/1932 Bougon 1 1 t v 1 1 .1 310/12 1 Inventors: o Izumidale, Kltakyushu; 1905.218 4/1933 Crago 188/164 x Susumu ltoh, Hitachi, both of Japan 2,006,759 7/1935 Edgar 193/38 X 2.786563 3/1957 Stuart 193/41 [731 Asslgme? Japan 3.225.228 12/1965 Roshala 1. 310/12 [22] Filed: May 16, 1972 Primary Examiner-Ev0n C. Blunk [2]] Appl' 253756 Ass/slant Exuminer1ames L. Rowland Armmey, Agent, or FirmCraig & Antonelli Foreign Application Priority Data May 17 1971 Japan 46-33487 57 ABSTRACT Nov. 24, 1971 Japan 11111111 .1 4693615 I Japan N 4693616 Silencing means for repressmg or reducing noise of impact between steel pipes being transferred by means 521 LS. Cl. I I I V h 193 4i 310/12. Of electromagnets provided between adjacent Skid 318/ rails such that magnetic circuits are formed by these 51 1111. c1. 865g 11/20 Electromagnets Skid rails and Pipes being [58] Field of Search 193/38-41' ferred- Magnetic forces by electromagnels 198/411 310/12. 318/135. 188/164 acts to cancel the acceleration of steel pipes rolling on l l l the skid rails to reduce the speed of the steel pipes [56] References Cited being transferred, thereby reducing the energy of im- UNITED STATES PATENTS pact between steel pipes for repressing or reducing 88/ X n01se at the time of impact between steel pipes. 952,493 3/1910 Atwood 1 1 t 1 1 1 l 164 1,673,740 6/1928 Eide 193/41 20 Claims, 8 Drawing Figures H w z' 1 J 1 4 p F POWER 1 SOURCE L 1 177 L 8 I 1'71 F1 1 11 m 11 1 11 rm H S1 1 1 A 9! 1 1 4 a a. m 1 )0 /v Q J n 1 n 1 1 n j J rm 1 rm 1 r1..

l l 1 LLJ L 5 r 1 I EQ I f "ln I J 1 [TI 1 a NLLJ I 1 .1 g 7/0 54 J 4b 9 I 1 [T1 17'] T1 5 1 l 15 I r' -"r' -3-' 5 a 5 /0 5 5 PATENIEDHAY 1 31915 3.882 981 SHEET 2 BF 4 SILENCING MEANS FOR STEEL PIPE PRODUCTION LINES This invention relates to silencing means for use in steel pipe production lines. In steel pipe production lines in steel plants, where the eventual products under manufacture and products are transferred by concon secutive roller conveyor lines, skid stations are provided at predetermined positions between adjacent roller conveyor lines for temporarily storing steel pipes for the purpose of inspection. The skid station consists of a plurality of transversal skid rails which are usually slanted to facilitate the transfer of steel pipes to the following conveyor line. In this skid station, however, great noise is generated due to impact among successively coming steel pipes and temporarily stored steel pipes. The impact between steel pipes creates noise of very large energy, resounding to far remote places, so that it constitutes a public problem where steel plants are operated night and day. Recently, in steel plants giving off great noise provision of means to repress or reduce such noise is mandatory. Heretofore proposed silencing means use rotary stoppers provided at the feedout end of slanted skid rails. However, noise still results from impact between the stoppers and steel pipe. Also, since the diameter of steel pipes transferred is not constant but various, a problem for the position of installation of the stoppers projecting to the side of the skid rails on which steel pipes rolls are encountered. Further, the stoppers wear as they are struck by steel pipes, so that they have a limited service life but their replacement is not easy. Furthermore, in order to transfer steel pipes to the following conveyor line means is required to release the stoppers acting to hold the steel pipes, which complicates the construction involved.

The noise mentioned above is generated as a major portion of the kinetic energy of the steel pipe is converted into sound. Mathematically, the impact energy E (in N.m) is given as where v and m is mass of pipe (in kg), v is velocity of centroid (in m/s), 1 is moment of inertia (in kg.m w is angular velocity of pipe periphery (in rad/s), g is gravitational acceleration (in m/s dis pipe inner diameter (in m), D is pipe outer diameter (in m), S is displacement of pipe (in m), and 9 is angle of inclination of skid rails.

As is apparent from the above equation, the impact energy E is proportional to the square of velocity v. Thus, the noise due to impact may be repressed or reduced by reducing the velocity of the steel pipe rolling over the skid rails.

One method to achieve this is to reduce the angle of inclination of the skid rails. However, a certain minimum inclination angle 8 is required for reduction or ef fective utilization of ground space or facilitating the transfer of steel pipes to the following conveyor line, so that it is practically difficult to sufficiently reduce noise by merely changing the inclination angle 9. In addition.

if it is intended to change inclination angle 6 to B l, the level and position of the following line should be shifted in consistence with the changed angle 6 l, which means awful change of installation.

Another method to reduce the steel pipe velocity is to bend the skid rails in an intermediate portion thereof so as to slow down the steel pipe in the bent portion. By this method, however, the steel pipe should roll over skid rails for an increased distance, which means that the possibility of causing damage to the steel pipe is increased. Besides, if the steel pipe completely loses its kinetic energy in the vicinity of the crown of the bent portion and turns to roll in the opposite direction due to its own weight, it will be struck by the following steel pipe.

As is shown, with the conventional measures it has been difficult to securely repress or reduce noise of impact of steel pipes generated in the skid station.

An object of the invention is to greatly reduce noise resulting from impact of transferred steel pipes rolling over skid rails.

Another object of the invention is to provide the possibility of freely controlling the speed of transferred steel pipes rolling over skid rails.

A further object of the invention is to provide a silencing means, which is capable of greatly reducing noise resulting in the transfer of longitudinally curved steel pipes over skid rails.

In accordance with the invention, electromagnetics are provided in skid rails to set up magnetic forces tending to cancel the acceleration of steel pipes rolling over the skid rails to thereby reduce the speed and hence the impact energy of steel pipes for repressing or reducing the noise of impact of steel pipes.

More particularly, electromagnetic coils provided between adjacent skid rails are energized to create closed magnetic circuits from the electromagnets through the skid rails and steel pipes, whereby braking forces are exerted to the steel pipes rolling over the skid rails.

The weight or mass of steel pipes vary with various outer diameters, lengths and other dimensions of the pipes. According to the invention, the extent of excitation of the electromagnets may be adjusted according to the weight of the pipe to thereby repress the transfer speed of the pipe for reducing the impact energy and impact noise.

In order for the invention to be fully understood, it will now be described with reference to the accompanying drawing, in which:

FIG. 1 is a schematic layout ofa skid station incorporating an embodiment of the silencing means according to the invention;

FIG. 2 is a side view of the skid station of FIG. I,

FIG. 3 is a fragmentary sectional view taken along line III-Ill in FIG. 1;

FIG. 4 is a layout of a skid station incorporating another embodiment of the silencing means according to the invention;

FIG. 5 is a side view of a skid station incorporating a further embodiment of the silencing means according to the invention;

FIG. 6 is a layout of a skid station incorporating a still further embodiment of the silencing means according to the invention;

FIG. 7 is a front elevational view of the skid station of FIG. 6;

FIG. 8 is a side view of a skid station incorporating a yet further embodiment of the silencing means according to the invention.

Referring now to FIGS. 1 to 3, which show one embodiment of the invention, reference numeral 1 designates a steel pipe feed-ii roller conveyor line installed on a foundation 2. Numeral 3 designates a steep pipe feed-out roller conveyor line also installed on the same foundation 2 and extending parallel to the fcedin roller conveyor 1 and at a lower level. Provided between these roller conveyor lines 1 and 3 are a plurality of suitably spaced, transversal parallel skid lines 4a to 40 at a certain inclination angle. These rails are supported on top of support legs 5.

Provided at the end of the skid rails adjacent the feed-in roller conveyor 1 is a steel pipe introducing means 6, which comprises a shaft 7 operated from a drive source not shown and a plurality of fetching nails 8 secured to the shaft. Extending between adjacent one of the skid rails 40 to 4e are a plurality of suitably spaced, longitudinal parallel core rods 9 of a magnetic material. The core rods 9 are secured by suitable means such as bolting or welding to the underside of the skid rails in a satisfactory magnetic relation thereto.

Electromagnetic coils 10 are wound on the individual cores 9 and connected through power supply lead L to a power source P.S., which is capable of controlling the excitation of coils 10. The electromagnetic coils 10 are energized such that N and S poles are provided at corresponding positions of alternate cores 9 and skid rails 40 to 4e.

Steel pipes 11 conveyed by the feed-in roller conveyor l are fetched by the steel pipe introducing means 6 and put on the skid rails 4a to 4e.

When the electromagnetic coils 10 are excited, N and S poles are provided at corresponding positions of alternate skid rails 4a to 4e, and the magnetic flux extends from these rails into adjacent space. In this state, a steel pipe 11 fetched by the steel pipe fetching means 6 and brought on the initial position on the skid rails 4a to 46 as shown by broken lines in FIG. 2, starts to roll over the skid rails due to its initial momentum and its own weight.

As the steel pipe I] is brought on the skid rails, the afore-mentioned magnetic flux extending from the skid rails into adjacent space gets to be substantially confined in closed magnetic loops formed by steel pipe 11, skid rails 4a to 4e and cores 9 between adjacent rails, as shown by arrows. These magnetic loops become shortest when the steel pipe 11 reaches a position right above the cores 9, and at which time the magnetic reluctance is minimum. Aiso, the steel pipe 11 on the skid rails always experiences magnetic forces of attraction tending to render the magnetic loops shorter. In other words. the cores 9 provide electromagnetic forces of attraction tending to increase the rolling speed of a steel pipe on their right side while providing forces tending to slow down a steel pipe on their left side. Thus, the steel pipe on the skid rails is accelerated at its positions on the right side of the individual cores while its speed is reduced at its positions on the left side of the cores. At the position mid way between two adjacent cores, the steel pipe experiences equal forces of attraction from both of these electromagnets. And at this point it rolls by virtue of its aquired speed and its weight. In the above manner, the rolling speed of the steel pipe may be extremely reduced compared with the case of absence of electromagnets. Thus, it is possi ble to reduce the impact energy E in equation 1 to thereby reduce the impact noise.

According to the invention, it is possible to appropri ately control the transfer speed of steel pipe 11 rolling over the skid rails irrespective of the weight of the steel pipe, which varies with difference in outer diameter, length and wall thickness of the pipe, by so arranging as to be able to control the exciting current through the individual coils 10 or vary the number of coils 10 that are energized.

The above speed control may result in residual magnetism in the steel pipe 11. If excessive residual magnetism is present, it sometimes happens that satisfactory welding of product steel pipes cannot be obtained. It has been found that if residual magnetism in the usual steel pipe is in exess of I00 gaus, imperfect welding of two steel pipes would result due to such residual magnetism. To avoid this inconvenience, the products are usually passed through a tie-magnetizing tunnel for tie-magnetization.

According to the invention, it is possible to reduce the residual magnetism in the steel pipe so as to dispense with the de-magnetizing treatment.

FIG. 4 shows another embodiment, with which the residual magnetism is reduced. In this embodiment, the skid rails 4a to 4e as mentioned above are provided with non-magnetic regions I2 spaced at a predetermined interval along the length of the rails. By this means, the skid rails may be made to assume opposite magnetic polarities on opposite sides of each nonmagnetic region 12.

With this construction, the direction of magnetic flux passing through the steel pipe 11 is inverted as the pipe passes each row of electromagnets consisting of cores 9 and coils 10. Thus, with the low frequency alternating magnetic flux the residual magnetism in the steel pipe is reducedv From the aspect of efficiently utilizing the exciting energy, it is possible to provide limit switches capable of detecting approaching steel pipes near the individual coils 10 for energizing the coils successively in the order of the direction of rolling of the steel pipe for a predetermined period. (In this case, it is necessary to determine the location of the individual switches by taking the rise time of the coil into consideration.)

Also, since maximum permissive exciting current (maximum current with which a steel pipe will not come to a standstill on the skid rails) for various steel pipes may be experimentally known, it is possible to achieve automatic transfer of steel pipes through com puter control based on empirical data.

In accordance with the invention, the impact energy may also be effectively reduced by substantially reducing the initial speed of the steel pipe 11 transferred by the steel pipe introducing means 6 onto the skid rails. Accordingly, the effect of reducing the impact noise may be promoted by incorporating means to reduce the initial speed of the steel pipe.

FIG. 5 shows a further embodiment intended to this end. In this embodiment, the end of each skid rail 4 on the side of the feed-in roller conveyor 1 is connected to a floating rail 13 supported for flexure. More particularly, each floating rail 13 is pivotally linked at one end through a pin 14 to the associated skid rail 4 and is resiliently supported by a spring 16 on a support leg 16.

In operation, when a steel pipe fetching and throwing means fetches a steel pipe 11 from the roller conveyor .i. l and introduces it to the skid rail side, while imparting an initial momentum to its, each floating rail 13 is rotated in the counterclockwise direction about the pin 14, with each spring 16 being compressed by the weight of the introduced steel pipe. As a result. the -ating rails 13 are orientated at an angle with respect to the direction of introduction of the steel pipes. so that they act to cancel the initial speed of the steel pipe. With this construction, by appropriately selecting the spring constants for the springs 16 it is possible to completely cancel the initial speed. The steel pipe with the initial speed reduced in the above manner rolls on the skid rails and is stored thereon similar to the previous embodiments.

While in this embodiment the floating character of the floating rails 13 is provided by the springs 16, it may as well be provided by other means such as pneumatic or hydraulic ones.

in the preceding embodiments, the individual skid rails are arranged with their top flush with one another, so that the steel pipe will roll in close contact with the individual skid rails to form closed magnetic loops. However. if the transferred steel pipe is curved or if the top of the individual skid rails are not flush with each other, desired magnetic forces may not be obtained due to gaps formed between the steel pipe and the skid rails. in such case. sufficient repression or reduction of impact noise cannot be expected. Further, to ensure required magnetic force provision of means to detect the state of magnetic loops and extra power consumption are necessary.

According to the invention. it is also possible to ensure good contact between steel pipe and skid rails for effectively exterting electromagnetic forces to the rolling steel pipe for the speed control thereof.

FIGS. 6 and 7 show another embodiment. which is intended to realize this, and in which some of the skid rails are floating rails.

Referring to these Figures, numeral 30 designates rail supports extending upright from a foundation 2. A plurality of skid rails 31 are supported on top of the rail supports 30. Among the skid rails 31, those designated as 31a are floating rails supported on respective rail supports 30 via associated springs 32. Connecting adjacent skid rails are core rods 33 of a magnetic material, which are connected to the associated fixed skid rails 31 by means of bolting or welding and to the associated floating ski'l rails 31a through a resilient conductor. The cores 33 carry respective coils 34 wound thereon. Means for exciting the coils 34 and lead lines thereto are not shown.

When a curved steel pipe rolls over the skid rails, the floating rails 31a change their level in conformity to the shape of the steel pipe passing on them by the flexing action of the respective springs 32. so that their contact with the steel pipe is maintained. Thus, the steel pipe can experience effective magnetic forces of magnetic loops formed as the coils 34 are energized to slow down its sp'-ed. so that he impact energy given in equation 1 :it the time of its impact with already stored steel pipe to repress or reduce noise generation.

he steel pipes fed in the skid station may not be of the same curved shape. Even if they are of the same shape. their orientation when they pass by certain noims of be individual rails may not be the same.

Therefore. if one floating rail 31a is greatly lowered by a steel pipe. the next steel pipe may not roll in contact with that floating rail 31a. Sometimes, one rail may hinder the contact between a steel pipe and an adjacent rail. If many floating rails 31a are out of contact with a steel pipe, the speed of that steel pipe will be increased to reduce its distance from the preceding steel pipe. and in an extreme case it will strike the preceding steel pipe giving rise to noise.

H6. 8 shows an arrangement with which the above disadvantage is overcome. ln this embodiment. each floating rail 31a consists of a plurality of sections a. b. and c (each being at least as long as the distance between two consecutively transferred steel pipes) so that a steel pipe may be independently supported on these sections.

The possibility of causing damage to the steel pipe as it jumps from one floating rail section to the next one may well be eliminated by rounding the feed-in end of each section or more securely by covering the rounded end of each section with a flexible material such as rubber.

While in the preceding embodiment the springs 32 are used to provide floating character to the floating rails, the floating character may as well be provided in other ways. for instance with pneumatic or hydraulic means. Also, the floating character of the rail may be made to be adjustable, so that each rail may serve as both a fixed rail and a floating rail. Further. where complicately curved steel pipes are handled or where correction of level difference among the individual rails is difficult, all the rails may be constructed as floating rails. By so doing, the level difference in the rails due to wear thereof may be absorbed, so that the service life may be increased.

What is claimed is:

l. A silencing means for use in steel pipe production line skid stations. said means comprising a plurality of skid rails for rolling a plurality of steel pipes, said rails being spaced from one another and inclined downwardly from a steel pipe feed-in end to a feed-out end, in use the steel pipes being fed to said steel pipe feed-in end one after another, said skid rails being provided with a plurality of non-magnetic regions dividing each said skid rail into a plurality of magnetic regions. magnetic bodies magnetically coupling corresponding magnetic regions of adjacent skid rails. exciting coils for providing predetermined magnetic flux extending in magnetic circuits each formed by the associated magnetic body, one of said steel pipes, and the magnetic regions of said adjacent skid rails, and means for continuously energizing said exciting coils such that said skid rails assume opposite magnetic polarities on opposite sides of each of said non-magnetic regions.

2. Silencing apparatus for use in elongated cylindrical steel member production line skid stations to reduce the noise occurring due to impact of a steel member upon another steel member on the skid and upon arrival in the region of a feed-out end of the skid station. the apparatus comprising a plurality of skid rails spaced from one another and inclined downwardly with respect to a horizontal plane from a steel member feed-in end to the feed-out end so as to permit the elongated steel members being fed one after another to roll downwardly from the feed-in end to the feed-out end under the force of gravity. and electromagnetic force means being continuously energized for controlling the speed of travel of the elongated steel members over the path between the feed-in end to the feed-out end and for creating a repelling force between adjacent steel members for spacing the steel members from one another to reduce the impact energy of the steel members in the region of the feed-out end and thereby lessen the noise resulting from impact.

3. Silencing apparatus according to claim 2, wherein said electromagnetic force means is disposed substantially in a single plane and lies below the top portion of said skid rails upon which the steel members roll.

4. Silencing apparatus according to claim 2, wherein said electromagnetic force means include at least one magnetic body magnetically coupling at least one pair of adjacent ones of said skid rails, and exciting coil means for providing predetermined magnetic flux extending in a magnetic circuit formed by said magnetic body, one of said steel members and said pair of skid rails,

5. Silencing apparatus according to claim 4, wherein a plurality of magnetic bodies are provided between adjacent ones of plural pairs of said skid rails.

6. Silencing apparatus according to claim 4, wherein a plurality of magnetic bodies are provided between adjacent ones of all of said skid rails.

7. Silencing apparatus according to claim 4, wherein a plurality of magnetic bodies are provided between at least one pair of adjacent ones of said skid rails at a predetermined interval in the longitudinal direction of said skid rails.

8. Silencing apparatus according to claim 4, wherein said means for energizing said exciting coil means energize said coil means such that the magnetically couplech adjacent skid rails assume opposite magnetic polarities,

9. Silencing apparatus according to claim 4, further comprising resilient support means for supporting at least one of said skid rails for flexure in the vertical direction.

l0. Silencing apparatus according to claim 4, wherein said skid rails each consist of a plurality of separate sections, and further comprising resilient support means for individually supporting each of said separate sections of said skid rails for flexure in the vertical direction.

11. A method for use in elongated cylindrical steel member production line skid stations to reduce the noise occurring due to impact of the steel member upon another steel member on the skid and a stop member in the region of the feed-out end of the skid station, the method comprising the steps of arranging a plurality of skid rails so as to be spaced from one another and downwardly inclined from the steel member feed-in end to the feed-out end of the skid station, permitting the steel members to roll downwardly one after another from the feed-in end to the feed-out end under the force of gravity, applying a magnetic force to the rolling steel members to control the speed of travel of the steel members over the path between the feed-in end to the feed-out end and to create a repelling force between adjacent steel members for spacing the steel members from one another, and lessening the noise resulting from impact of the steel member upon another steel member and a stop member by reducing the impact energy of the steel member in the region of the feed-out end,

12. A method according to claim 11, the step of applying a magnetic force includes the steps of arranging at least one magnetic be ly for magnetically coupling at least one pair of adjacent ones of the skid rails, providing exciting coil means to provide a predetermined magnetic flux and energizing the exciting coil means to provide the predetermined magnetic flux extending in a magnetic circuit formed by the magnetic body, one of said steel members, and the pair of skid rails.

13. A method according to claim 12, including the step of energizing the exciting coil means so that the magnetically coupled skid rails assume opposite magnetic polarities.

14. A method according to claim ll, including the step of resiliently supporting at least one of the skid rails for flexure in the vertical direction.

15. In an elongated cylindrical steel member production line skid station wherein elongated cylindrical steel members are fed one after another to the skid station, the improvement comprising silencing apparatus for reducing noise occurring due to impact of the steel members upon arrival in the region of a feed-out end of the skid station, the apparatus including a plurality of skid rails spaced from one another and inclined downwardly with respect to a horizontal plane from a steel member feed-in end to a feed-out end so as to permit the elongated steel members being fed one after another to roll downwardly from the feed-in end to the feed-out end under the force of gravity, the feed-out end of the skid station being provided with a stop memher, and electromagnetic force means for controlling the speed of travel of the elongated steel members over the path between the feed-in end to the feed-out end for reducing the impact energy of the steel members on one of the stop member and another of said steel members in the region of the feed-out end so as to lessen the noise resulting from such impact, said skid rails being provided with a plurality of non-magnetic ,ntgions along the length thereof dividing each of said skid rails into a plurality of magnetic regions, said wtromagnetic force means including a plurality ofinagnetic bodies being provided for magnetically coupling corresponding magnetic regions of adjacent skid rails, and exciting coil means providing predetermined magnetic flux extending in a magnetic circuit formed by the associated magnetic body, and one of steel members, and the magnetic regions of said skid rails, and means for energizing said coil means such that said skid rails assume oppo site magnetic polarities on opposite sides of each of said non-magnetic regions.

16. Silencing apparatus according to claim 15, wherein said energizing means continuously energizes said coil means.

17. A silencing means for use in steel pipe production line skid stations, said means comprising:

at least three essentially parallel skid rails for rolling a plurality of steel pipes, said rails being spaced from one another and inclined downwardly from a steel pipe feed-in end to a feed-out end, in use fiie steel pipes being fed to said steel pipe feedin end one after another;

at least one magnetic body arranged at each of the spaces between said skid rails from said feed-in end to said feed-out end, every adjacent two of said skid rails being connected by at least one magnetic body,

electromagnetic coils for individually magnetizing said magnetic bodies; and

9 10 means for continuously energizing said electromagone of the stop member and another of said pipes in the netic coils so that adjacent Skid rails are magneregion of said feed-out end so as to lessen the noise retized in opposite polarity to each other when said Sulting f h impact. elecimmagnetic coils are energized whereby a 19. A silencing means according to claim 17, wherein magneflc cifcuit i f g 5 a plurality of magnetic bodies are provided between adnetic body, its ad acent pair 0 s id rat s an one o jaunt Ones of a Said skid mus smd to retard the travel of smd pipe down the 20. A silencing means according to claim 17. wherein incline. A Silencing means according to claim wherein a plurality of magnetic bodies are provided between at said feed-out end of said skid station is provided with 1 least l of adjafem ones of i i l at a P :1 stop m ber, d th magnetic i i hi h i determined interval in the longitudinal direction of said formed serves for controlling the speed of travel of said kid rails.

pipes for reducing the impact energy of the pipes on

Claims

1. A silencing means for use in steel pipe production line skid stations, said means comprising a plurality of skid rails for rolling a plurality of steel pipes, said rails being spaced from one another and inclined downwardly from a steel pipe feed-in end to a feed-out end, in use the steel pipes being fed to said steel pipe feed-in end one after another, said skid rails being provided with a plurality of non-magnetic regions dividing each said skid rail into a plurality of magnetic regions, magnetic bodies magnetically coupling corresponding magnetic regions of adjacent skid rails, exciting coils for providing predetermined magnetic flux extending in magnetic circuits each formed by the associated magnetic body, one of said steel pipes, and the magnetic regions of said adjacent skid rails, and means for continuously energizing said exciting coils such that said skid rails assume opposite magnetic polarities on opposite sides of each of said non-magnetic regions.

2. Silencing apparatus for use in elongated cylindrical steel member production line skid stations to reduce the noise occurring due to impact of a steel member upon another steel member on the skid and upon arrival in the region of a feed-out end of the skid station, the apparatus comprising a plurality of skid rails spaced from one another and inclined downwardly with respect to a horizontal plane from a steel member feed-in end to the feed-out end so as to permit the elongated steel members being fed one after another to roll downwardly from the feed-in end to the feed-out end under the force of gravity, and electromagnetic force means being continuously energized for controlling the speed of travel of the elongated steel members over the path between the feed-in end to the feed-out end and for creating a repelling force between adjacent steel members for spacing the steel members from one another to reduce the impact energy of the steel members in the region of the feed-out end and thereby lessen the noise resulting from impact.

4. Silencing apparatus according to claim 2, wherein said electromagnetic force means include at least one magnetic body magnetically coupling at least one pair of adjacent ones of said skid rails, and exciting coil means for providing predetermined magnetic flux extending in a magnetic circuit formed by said magnetic body, one of said steel members and said pair of skid rails.

8. Silencing apparatus according to claim 4, wherein said means for energizing said exciting coil means energize said coil means such that the magnetically coupled adjacent skid rails assume opposite magnetic polarities.

10. Silencing apparatus according to claim 4, wherein said skid rails each consist of a plurality of separate sections, and further comprising resilient support means for individually supporting each of said separate sections of said skid rails for flexure in the vertical direction.

11. A method for use in elongated cylindrical steel member production line skid stations to reduce the noise occurring due to impact of the steel member upon another steel member on the skid and a stop member in the region of the feed-out end of the skid station, the method comprising the steps of arranging a plurality of skid rails so as to be spaced from one another and downwardly inclined from the steel member feed-in end to the feed-out end of the skid station, permitting the steel members to roll downwardly one after another from the feed-in end to the feed-out end under the force of gravity, applying a magnetic force to the rolling steel members to control the speed of travel of the steel members over the path between the feed-in end to the feed-out end and to create a repelling force between adjacent steel members for spacing the steel members from one another, and lessening the noise resulting from impact of the steel member upon another steel member and a stop member by reducing the impact energy of the steel member in the region of the feed-out end.

12. A method according to claim 11, the step of applying a magnetic force includes the steps of arranging at least one magnetic body for magnetically coupling at least one pair of adjacent ones of the skid rails, providing exciting coil means to provide a predetermined magnetic flux and energizing the exciting coil means to provide the predetermined magnetic flux extending in a magnetic circuit formed by the magnetic body, one of said steel members, and the pair of skid rails.

14. A method according to claim 11, including the step of resiliently supporting at least one of the skid rails for flexure in the vertical direction.

15. In an elongated cylindrical steel member production line skid station wherein elongated cylindrical steel members are fed one after another to the skid station, the improvement comprising silencing apparatus for reducing noise occurring due to impact of the steel members upon arrival in the region of a feed-out end of the skid station, the apparatus including a plurality of skid rails spaced from one another and inclined downwardly with respect to a horizontal plane from a steel member feed-in end to a feed-out end so as to permit the elongated steel members being fed one after another to roll downwardly from the feed-in end to the feed-out end under the force of gravity, the feed-out end of the skid station being provided with a stop member, and electromagnetic force means for controlling the speed of travel of the elongated steel members over the path between the feed-in end to the feed-out end for reducing the impact energy of the steel members on one of the stop member and another of said steel members in the region of the feed-out end so as to lessen the noise resulting from such impact, said skid rails being provided with a plurality of non-magnetic regions along the length thereof dividing each of said skid rails into a plurality of magnetic regions, said electromagnetic force means including a plurality of magnetic bodies being provided for magnetically coupling corresponding magnetic regions of adjacent skid rails, and exciting coil means providing predetermined magnetic flux extending in a magnetic circuit formed by the associated magnetic body, and onE of steel members, and the magnetic regions of said skid rails, and means for energizing said coil means such that said skid rails assume opposite magnetic polarities on opposite sides of each of said non-magnetic regions.

17. A silencing means for use in steel pipe production line skid stations, said means comprising: at least three essentially parallel skid rails for rolling a plurality of steel pipes, said rails being spaced from one another and inclined downwardly from a steel pipe feed-in end to a feed-out end, in use the steel pipes being fed to said steel pipe feed-in end one after another; at least one magnetic body arranged at each of the spaces between said skid rails from said feed-in end to said feed-out end, every adjacent two of said skid rails being connected by at least one magnetic body; electromagnetic coils for individually magnetizing said magnetic bodies; and means for continuously energizing said electromagnetic coils so that adjacent skid rails are magnetized in opposite polarity to each other when said electromagnetic coils are energized, whereby a magnetic circuit is formed by each respective magnetic body, its adjacent pair of skid rails and one of said pipes to retard the travel of said pipe down the incline.

18. A silencing means according to claim 17, wherein said feed-out end of said skid station is provided with a stop member, and the magnetic circuit which is formed serves for controlling the speed of travel of said pipes for reducing the impact energy of the pipes on one of the stop member and another of said pipes in the region of said feed-out end so as to lessen the noise resulting from such impact.

19. A silencing means according to claim 17, wherein a plurality of magnetic bodies are provided between adjacent ones of all said skid rails.

20. A silencing means according to claim 17, wherein a plurality of magnetic bodies are provided between at least one pair of adjacent ones of said skid rails at a predetermined interval in the longitudinal direction of said skid rails.