US3415392A - Workpiece positioning device - Google Patents

Description

1968 JOHNSON, JR 3,415,392

WORKPIECE POSITIONING DEVICE Filed March 16, 1966 IN VEN TOR.

AAA E JOHNSON, J9.

United States Patent Oflice 3,415,392 WORKPIECE POSITIONING DEVICE Lane Johnson, Jr., Carnegie, Pa., assiguor to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 16, 1966, Ser. No. 534,781 Claims priority, application Great Britain, Mar. 31, 1965, 13,747/ 65 4 Claims. (Cl. 21423) ABSTRACT OF THE DISCLOSURE The disclosure of this invention relates to a slab reheating furnace of the type used in the operation of a hot strip mill. The disclosure teaches in combination with an horizontal slab reheating furnace and a roller table arranged below the furnace for conveying slabs away from the furnace, the employment of a curved shaped discharge chute arranged between the furnace and the table. The curved surface of the chute is constructed so that, notwithstanding the differences in size and weight of the slabs, their energy during the descent from the furnace to the table will be dissipated prior to passing the center of the table. The invention also teaches the employment of a pusher ram mounted beneath the furnace designed to position slabs on the center of the table once they have come to rest on the table.

The present invention relates to slab transfer and positioning apparatus for use in conjunction with a workpiece reheating furnace, say, for example, with a furnace provided to reheat the workpieces, such as slabs, to a rolling temperature. More particularly, the present invention relates to a slab handling and transferring device which will not only entirely eliminate the destructive potential energy of descending slabs but completely eliminate the need of furnishing a device for dissipating the energy of each slab, as it is allowed to slide down from the elevation of the furnace onto a table arranged below the hearth of the furnace.

The rolling of strip by a modern hot strip mill from slabs currently of the order of 80,000 lbs. and heavier, measuring in usual :cases to 12. inches x 76 inches x 32 feet, has presented a serious problem in transferring the slabs from the furnace to the table provided to transport slabs to the rolling mill. It was customary in previous mills, which handled much smaller slabs than described above, to arrange the furnace table approximately 7 feet below the hearth of the furnace. In this arrangement slabs were successively pushed from the furnace by a pusher means arranged at the entry side of the furnace wherein each slab then slid down a chute or skid onto the table. In view of the energy built up by the slab during its descent, it was customary to provide in conjunction with the table, at the side opposite the furnace, a bumper apparatus engageable by the slab for dissipating its energy and allowing the slab then to come to rest on the table. Such an arrangement is shown and described on page 626 of The Making, Shaping and Treating of Steel, eighth edition, published by United States Steel Corporation, 1964. When the size and weight of the slabs were increased to the size now customary in operating a modern hot strip mill, it was not surprising that serious problems developed with respect to transferring of the slabs from the furnace to the table. In some cases, the energy developed was so great as to cause damage and breakage to the table and bumper arrangement in addition to resulting in objectionable marking of the slabs.

The seriousness of the problem is indicated by the concentrated effort of the industry to find an acceptable 3,415,392 Patented Dec. 10, 1968 arrangement free from energy dissipating problems for transferring a slab from the furnace to the table. Examples of some of the results of this effort are illustrated in the following recently issued US. patents: Patent No. 2,515,- 675 which issued to G. Tree on July 18, 1950, Patent No. 3,129,829 which issued to H. C. Ferguson on Apr. 21, 1964, and Patent No. 3,143,337 which issued to H. A. Rees et al. on Aug. 4, 1964. The Ferguson patent, No. 3,129,829, illustrates rather realistically the elevational difference between the furnace hearth and the table wherein an appreciation can be gained of the build-up of potential energy in the slab as it slides downwardly from the furnace onto the table. Of course, in this patent, to reduce the deleterious effect of allowing the slab to fall, the slab is actually caught midway in its descent, rotated and set down on the table.

A still further suggestion to alleviate this acute problem, which is made Worse by the desire to roll heavier and larger slabs, has been to lower the furnace to eliminate the elevational difference between the furnace and table and to provide a horizontal slab extractor. In this arrangement, since there is virtually no difference between the elevation of the hearth and the table, the extractor can be arranged on the side of the table opposite the furnace and moved into the furnace hearth. The extractor then can lift a slab from the hearth, after which it will be retracted to dispose the slab on the table. While this design will, of course, completely eliminate any detrimental consequences of allowing the slab to'slide from the furnace onto the table, it has created other problems which appear to be of considerable magnitude. One of these is addressed to the fact that in using an extractor-type slab transfer, a serious maintenance problem is created because the hydraulic and mechanical components of the device are subject to heavy accumulation of scale. It is also objectionable since it entails considerable heat losses, as well as requiring that certain extractor components be subjected to the radiation and direct heat from the furnace for a considerable period of time. Another serious objection is that the design has eliminated the knuckle joint of the furnace hearth, which affords a significant advantage. This term knuckle has reference to the intersection where the horizontal portion of the hearth meets with the inclined portion leading to the table. In employing a knuckle joint, the slabs, should they become inadvertently fused together during the reheating process, are automatically separated when the first slab is caused to fall over the joint. In employing a slab extractor device, there is no way of assuring that the two adjacent slabs will not inadvertently adhere to each other when the attempt is made to remove a leading slab.

The present invention eliminates each and every one of the disadvantages of the arrangements of existing mills, as well as those arrangements which have followed, yet retaining the knuckle joint feature. More particularly, the present invention provides for a considerable reduction in the elevational differences between the top of the table and the hearth surface of the furnace, thus enabling the knuckle joint to be retained, but at the same time permitting a considerable reduction in the potential slab energy and wherein the furnace and table are bridged by a slab transfer member, so proportioned and arranged that for the entire range of slabs the energy of the slabs built up in their descent from the furnace will be dissipated prior to the slabs passing beyond the table, and preferably as soon as they have fallen a sufficient distance onto the transfer member to enable a pusher element arranged beneath the furnace to engage the one side of the slabs and push them off the transfer member, if necessary, onto the table where the slabs can be centered.

In the preferred arrangement there is provided a customarily constructed slab furnace including a knuckle joint. Between the delivery end of the furnace and the adjacent slab table, there is provided a slab transport member made up of several sections. The transport member will have a slab supporting surface configured of an are or an arc and straight surface, which is nevertheless developed with reference to the range of slabs to be handled so as to assure that the maximum weighted slab will not be passed beyond the center of the table, and preferably that the slab will stop after it has slid down the transport member only sufficiently far enough to enable the reciprocating pusher designed to pass through adjacent sections of the transport member to engage the slab and push it onto the table. In addition, there may be provided a means for raising the pusher up through the adjacent sections of the transfer member, wherein a portion of the pusher will be positioned to engage the adjacent surface of the slab, in combination with means for moving the pusher towards the table so as to transport the slab onto the table.

It is a further object of the invention to provide, if desired, an automatic means for so controlling the traverse of the pusher to automatically position the slab, notwithstanding a considerable variation in width, at the center of the table.

The above features and advantages will be better appreciated when the following description is read along with the accompanying drawing, which consists of:

An elevational view of a preferred embodiment of the present invention employed in combination with a slab furnace for a hot strip rolling mill.

With reference to this drawing, there is illustrated schematically a slab furnace 10, which, as previously noted, can be of ordinary construction and wherein slabs are progressively and successively advanced for reheating to the rolling temperature, say of the order of 2250 F. or more. At the discharge side of the furnace there is provided a customary furnace door 11, which is opened and closed by means not shown. Adjacent to the inside wall of the furnace door when the latter is in its closed position, there is a knuckle joint 12 over which each slab passes prior to discharge from the furnace. Cooperating with the joint and extending between the furnace and a slab table 13, there is provided a slab transfer chute or skid 14. This chute, for a reason to be explained hereinafter, is made in a number of sections and is designed to support each slab during its transfer from the hearth of the furnace to the table 13. As indicated by one of the aforesaid patents, the table consists of a number of motor-driven rollers, only one of which is shown in the drawing, in which connection the drawing illustrates the roller being supported on one end in a girder in a customary manner. It will be noted with respect to table 13 that the drawing illustrates a maximum and a minimum slab, which slabs, it should be mentioned, have not as yet been centered on the table.

Turning now to the skid 14, it is important to realize that in the present invention the elevation between the top of the rollers of the table 13 and the hearth of the furnace 10 or the knuckle joint 12 is considerably re duced over previous designs incorporating skids. In fact, it is a feature of the present invention to maintain this elevation only sufficiently to allow the slab to fall down from the furnace, thus to break any adherence to a previous slab and pass sufficiently down the skid so as toenable the pusher to be brought up behind the slab. As to the other extreme, the slope of the skid is designed to prevent any slab from passing beyond the center of the table. Thus, by this arrangement, the slab is allowed to develop only sufficient energy by its descent so as to cause a predetermined range of downward displacement which is a function of the height and contour of the skid 14. In this arrangement, therefore, there is no need of a heavy bumper structure on the opposite side of the table, but instead, if such is deemed desirable, a customary table sideguard can be used or none at all.

It will be noted that the skid 14 takes the form of an arc of a circle, which, in some respects, presents a very desirable tangential relationship between the bottom of the skid and the adjacent top surface of the rollers so as to provide a smooth transfer action. However, depending on the particular requirements, the configuration of the slab supporting surface of the skid, as previously noted, may be different from that which is illustrated and may take, for example, the form of a compound curve or a combination of a straight and curve or some other form. The important matter being that the slab is allowed to generate only enough energy during its descent to cause it to break away from the furnace and move away from the door, but not sufficient to allow the slab to develop such a force as to allow it to pass beyond the center of the table.

It was previously noted that the skid 14 is made in sections. This is to provide two or more separations between them and to enable two or more slab pusher heads 17 to'be raised between the skid sections, after which the heads can be traversed towards the table to push the slab off the skid, should the slab have come to rest thereon, and in any event, onto the table 13. As shown the pusher heads 17 are an integral part of a ram 18 which is provided with a rack 19 that meshes with a pinion 20, the pinion being driven by a motor, not shown. The ram 18 is raised in an operative position by a piston cylinder assembly 21 which is connected to the ram by a pair of rollers 26 and 27. It is important to note that the entire slab pusher assembly is located beneath the furnace where it will be free from scale and radiant heat.

Returning now to the two maximum and minimum slabs illustrated on the table 13, it is to be appreciated that the represented position of the two slabs are meant to indicate the positions they will assume after their energy has been dissipated by the friction generated between the slab and the skid 14. Once so positioned the ram head 17 will be advanced to move the slab in the center of the table. In this connection the drawing illustrates in phantom a head 17 in its pushing position against the smaller slab.

Another advantage of the present invention, not previously noted, is discernible in referring to the drawing in comparison with the older designs employing skids. It will be observed that the reduction in elevation between the furnace and the table in the present invention will re- 'sult in a lessening of the tilting of the slab as it falls onto the skid which will reduce heat losses since the furnace door will not need to be opened as far. In the illustrated arrangement the elevational difference between the table and the hearth is approximately fifteen inches, the arrangement being designed to handle a range of slabs measuring 20 inches x 5 inches x 32 feet in one case and up to 76 inches x 10 inches x 3.2 feet in another case. The heaviest slab will weigh approximately 83,600 lbs.

For the above, it can be seen that the present invention allows the maintaining of the knuckle joint of the furnace, thereby enabling a realization of the advantages that flow from the employment of the joint which were previously noted; the slab is stopped after a minimum travel subsequent to its discharge from the furnace, which travel is controlled to be just far enough to allow a pusher element to engage the adjacent side of the slab to effect a transfer from the furnace to the table. Thus, the energy created in the descent of the slab, while not entirely eliminated, is not allowed to damage the equipment, but used to its fullest advantage in carrying out the primary object of transferring the slab. This is done in such a way that there is no necessity of providing means either p to strengthen the table itself or in providing the elaborate bumper mechanism to dissipate the energy of the slab created by its descent.

The present invention is capable of being adapted for other uses and being modified and varied to meet the specific requirement without departing from its scope.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In combination with a furnace and a table spaced from said furnace and at a lower elevation therefrom for receiving workpieces of various parameters and conveying them away from the furnace,

a workpiece transfer means arranged between said furnace and table for transferring workpieces from said furnace directly to said table,

a workpiece pushing means for moving a workpiece transferred by said transfer means from a point below the upper end of said transfer means to a predetermined point on said table,

said transfer means having a workpiece engaging surface so constructed and arranged relative to the varying parameters of the workpieces and the difference in elevation of the furnace and table that the energy of the descending workpieces will be dissipated prior to passing said predetermined point on said table and within an area defined by said two points.

2. In combination with a furnace and a table in accordance with claim 1 wherein said furnace has a discharge opening,

a door for closing said opening after a workpiece has passed therethrough,

a knuckle joint in said furnace over which each workpiece pa'sses immediately prior to passing through said opening,

said table made up of spaced-apart rollers having their axes in a plane parallel to the longitudinal axis of the furnace,

wherein said workpiece transfer means comprises a number of spaced-apart sections, and wherein through the openings formed thereby said pushing means extends for engagement with a workpiece.

3. In combination with a furnace and table in accordance with claim 2, wherein said pushing means are located beneath said furnace so as not to be subject to deposits of scale that form on the workpieces and collected by said transfer means, and

wherein said pushing means includes upright workpiece engaging fingers constructed to pass into the openings formed by the sections of said transfer means, including means for advancing said pushing means towards and away from said table and separate means for raising and lowering said pushing means.

4. In combination with a discharge station and a table in accordance with claim 2, wherein the construction of said workpiece engaging surfaces of said transfer means takes the form substantially of an arc of a circle, the lower portion of which is tangentially disposed relative to the top of the rollers of said table.

References Cited UNITED STATES PATENTS 1,127,315 2/1915 Swindell 214-48 1,467,541 9/1923 Ford 193-1 X 2,880,844 4/1959 Vogeli 198-26 2,954,115 9/1960 Engleson et a1. 198-1221 3,243,059 3/1966 Kalberkamp 214-26 ROBERT G. SHERIDAN, Primary Examiner.

US. Cl. X.R. 1931; 198-59

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