US3740989A

US3740989A - Strip mill entry guides

Info

Publication number: US3740989A
Application number: US00129897A
Authority: US
Inventors: A Petros
Original assignee: Mesta Machine Co
Current assignee: MESTA ENGINEERING COMPANY APARTNERSHIP OF PA
Priority date: 1971-03-31
Filing date: 1971-03-31
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26
Also published as: FR2184517B1; DE2223150A1; FR2184517A1

Abstract

An entry guide mechanism comprises upper and lower platens positioned to receive an elongated workpiece therebetween. A pivotably mounted support is secured to the upper platen for pivotally supporting the upper platen, and a pivotally mounted support is secured to the lower platen for pivotally mounting the lower platen. An angularly displacing drive mechanism is secured to at least one of the pivoted supports to pivot portions of the platens toward one another to clamp the workpiece therebetween. The pivotal mountings for the platens conform the attitudes thereof with that of an adjacent segment of the workpiece.

Description

United States Patent [191 Petros [4 June 26, 1973 STRIP MILL ENTRY GUIDES Primary Examiner-Charles W. Lanham [75] Inventor: Andrew J. Petros, Oakdale, Pa. Examme' RPbn Rose Attorney-Donn J. Smith [73] Assignee: Mesta Machine Company,

s a 57 ABSTRACT [22] Filed: M81. 31, 1971 App]. No.: 129,897

16 Claims, 8 Drawing Figures STRIP MILL ENTRY GUIDES The present invention relates to entry guides for a strip mill and more particularly to entry guides of the character described which are uniquely useful in threading the rolling mill and in minimizing the problems involved in manipulation and of the entry guides. The entry guides are especially characterized by adjustability to differing strip widths and for withdrawal from the moving strip or other elongated workpiece during operation of the mill to minimize wearing of the entry guides can. The entry guides quickly and efficiently clamp the strip during.tailing-out thereof.

In the operation of strip rolling mills, mill entry guides are usually employed at each mill stand to guide the lead end of the strip to the bite of the work rolls. The guides are useful in minimizing tail end slap when tailing-out in a tandem strip mill.

In previous arrangements of such entry guides, the guides have not been capable of properly assuming the attitude of the strip going through the mill stand. This has resulted in undesirable wearing configurations on the boards or liners of the entry guides, which, of course, has markedly decreased the useful lives thereof. Without proper platen attitudes, clamping of the strip during tailing-out is difficult and inefficient. It is difficult also to lower many known forms of entry guides below the strip pass line to permit passage of the strip free of the entry guides when strip tension has been established between successive mill stands. Accordingly excessive wear on the boards or liner of the bottom platen has been a problem for this reason also.

Previous entry guides have required changing of the platen boards or of the lower platen itself for readjustment of the sideguides of the mill entry guides for diffe'ring widths of the strip or other elongated workpiece entering the rolling mill. Such sideguides for the most part have been provided only at entrance or exit of the entry guides, and this has resulted in considerable difficulties in squaring-up the strip during threading of the rolling mill.

In general previous mill entry guides are disadvantaged owing to a lack of maneuverability of their upper and'lower platens or the like. Known entry guides therefore have suffered from limited utility, particularly during threading and tailing-out of the mill, and in many cases have interfered with the roll changing operation. For many applications the clamping forces available by coaction of the platens of known mill entry guides have been inadequate for maintaining a proper strip tension.

Despite their lack of maneuverability and flexibility in general and the lack of adequate provisions for accommodating a variety of strip widths, previous mill entry guides have been unduly complicated in construction. Difficulties in manufacturing of known mill entry guides and in their maintenance have therefore been experienced. I

The present invention overcomes these disadvantages of the prior art by providing novel mill entry guides of a unique and unexpected configuration, wherein the guides are designed to assume the attitude of the strip as it is threaded to the associated work rolls of the mill. This is accomplished by an unusual pivotal action of the platens of the guides to prevent undue wearing of boards or other liner material. At the same time, the clamping capability of the platens is enhanced. Means are provided for quickly lowering the lower platen of the entry guides to permit clear passage of the strip when tension has been established between successive mill stands. Pivoting of the platens, as noted above, prevents uneven wear of the liners of the platens. On the other hand the ability to withdraw the lower platen from the pass line of the strip extends the life of the entry guides particularly the lower platen.

A novel and unexpected arrangement of edge guides are provided both at the entrance and exit of the entry guides for squaring up the strip and facilitating movement of the strip into the bite of the mill rolls. This edge or side guide arrangement has been mechanically simplified and requires less maintainence than previous designs. Moreover, the unique arrangement of sideguides of the invention permits facile changing of strip widths without the necessity of changing the platens or their liners or of substituting differing edge guides. My unique entry guide arrangement is capable of exerting greater clamping forces than known forms of entry guides. These clamping forces are readily variable as required by specific operational conditions of the mill. The top platen can be stabilized at a semi-rigid position for strip threading purposes. However, as noted above the pivotal action of the top platen permits the entry guides to assume the attitude of the adjacent strip segment as it is being threaded. Soft clamping of the strip can be accomplished by the entry guides by suitable biasing means associated for example with the clamp cylinders. Actuating means are additionally coupled to the entry guides for retracting the guides away from the mill rolls in the direction of the strip pass line to facilitate roll changing. At this retracted position the bottom platen can be used as an apron for strip threading purposes.

These desirable results are accomplished unexpectedly by providing an entry guide mechanism comprising upper and lower platens positioned to receive strip or other elongated workpiece therebetween, a support secured to said upper platen for supporting said upper platen, a pivotally separate support secured to said lower platen for pivotally mounting said lower platen independently of said upper platen, and drive mechanism secured to at least one of said supports to elevate at least one of said platens toward one another to clamp said workpiece therebetween, the pivotal mountings for said platens conforming the attitudes thereof with that of an adjacent segment of said workpiece.

A similar mill entry guide mechanism is also desirably provided wherein an elevating mechanism is provided for each of said platens to facilitate said clamping and to conform said platens to differing pass lines of said workpiece and to withdraw said platens from said pass lines when said workpiece is supported independently thereat.

A similar mill entry guide mechanism is also provided wherein one of said platens is provided with edge guide mechanisms transversely slidably mounted thereon for engaging and guiding the lateral edges respectively of differing widths of said workpiece.

A similar mill entry guide mechanism is also provided wherein two juxtaposed pairs of said edge guides are so mounted on said one platen for squaring-up said workpiece relative to said entry guides mechanism.

A similar mill entry guide'mechanism is also desirably provided wherein the pivot support for said lower platen is mounted on a carriage forming part of said entry guide mechanism and movable longitudinally of said workpiece. 1

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same. The accompanying drawings illustrates certain presently preferred embodiments of the invention and certain presently preferred methods of practicing the same, wherein:

FIGS. 1A and 1B constitute a composite, vertically sectioned view of one form of the novel entry guides of the invention illustrated in conjunction with a four-high mill stand, and taken along reference lines 1-1 of FIGS. 3A and 38;

FIG. 2 is a top plan view of the entry guides as shown in FIG. 1A, partially in section and with parts removed to show the invention more clearly;

FIGS. 3A and 3B constitute a composite, partially sectioned view of the apparatus as shown in FIG. 2 and taken along reference line III-III thereof;

FIG. 4 is a partial side elevational view of the apparatus as shown in FIGS. 3A and 3B, partially in section, and taken along reference lines IVIV thereof;

FIG. 5 is a partial, vertically sectioned view of the apparatus as shown in FIG. 1B and taken along reference line V-V thereof;

FIG. 6 is a horizontally sectioned view of the apparatus as shown in FIG. 5 and taken along reference line VI-VI thereof;

Referring now more particularly to the drawings, the entry guide mechanism shown therein comprises a pivoted upper platen 22 and a pivoted lower platen 24. The upper platen 22 includes a steel supporting plate 26 to which can be secured wooden liner boards 28 in a conventional manner. The supporting plate 26 is pivoted from a pivot shaft 30 extending transversely of the entry guides 20 and of the direction of strip travel (arrow 32), by a pair of supporting bracket assemblies 34 (FIG. 2). The bracket assemblies 34 terminate in pillow block arrangements 36 for clamping engagement with the pivot shaft 30. In the illustrated arrangement each bracket assembly 34 includes a pair of relatively closely spaced bracket members 34a, which are welded or otherwise secured to the supporting plate 22. The pivot shaft 30 assures that both sides of the upper platen move together and for this purpose is provided at each end with a pinion gear 38 (the gear at the right end only is shown in FIG. 3). A stationary, generally vertically disposed rack 40 is rigidly mounted at each end of the pivot shaft 30 and at substantially identical elevations. The racks 40 are enmeshed respectively with the pinions 38 throughout the range of vertical movement of the shaft 30 and the upper platen 22. When the upper platen 22 and its pivot shaft 30 are elevated by cylinders 72 (described below) relative to the strip pass lines 42, 44, both ends of the shaft 30 will be raised and lowered through identical distances. This will prevent the upper platen from canting transversely of the strip and the lower platen 24. The pass lines 42, 44 respectively represent exemplary maximum and minimum pass lines of the strip or other elongated material traverling in the direction denoted by arrow 32. The pass lines 42, 44 are determined conventionally by maximum and minimum diameters of work rolls 46, 48 respectively. In this arrangement, the supporting framework 49 is bolted to associated mill housings 51 to support the upper platen 22 and associated components (FIG. 3A).

The trailing edge portion of the liner boards 28 is beveled slightly such that the portion 50 can be supported generally parallel to the pass lines 42, 44 and to the adjacent surface of the platen 24. Means described below are provided for raising and lowering each of the

platens

22, 24 to engage the strip substantially at or between the pass lines 42, 44. As the attitude of the strip may deviate from the illustrated pass lines during the threading operation, each of the

platens

22 or 24 can be pivoted either separately or together to follow any anticipated changes in strip attitude. The upper platen 22 can be pivoted as described above, while the lower platen 24, including support plate 52 and wooden liner boards 54, can be pivoted about stub shafts 56 (FIGS. 5 & 6), as described below.

During threading of the mill, the

platens

22, 24 are maintained in a funnel disposition (FIG. IE) to facilitate feeding the head end of the strip to the adjacent work rolls. The attitude is maintained as to the upper platen 22 by a pair of attitude springs (FIGS. 1A, 2) acting on pivot shaft 30 and stop 57, when the cylinders 72 (described below) are actuated to raise the upper platen 22. FIGS. 1A and 1B show the upper platen in its upper most elevation or funnel] disposition. In its running position the upper platen is lowered by cylinders 72 to rest on the balancing springs 75 (described below) whereat the upper platen is supported closely adjacent and generally parallel to the running strip. In the illustrated case the upper platen can be supported about one inch above the moving strip. This greatly facilitates tail end clamping when the strip tails out.

Continuing the description of the upper platen 22 and its pivoting and elevating components, the upper platen 22 desirably is T-shaped as better shown in FIG. 2 of the drawings. The aforementioned bracket assemblies 34 are securedto the end portions respectively of a cross arm portion 58 of the upper platen. The leg portion 60 of the T-configuration is sufficiently narrow to pass between strip edge guides denoted generally by

reference characters

62, 64 at the minimum opening thereof as denoted by their

chain outline positions

62a, 64a in FIG. 3. The T-configuration of the upper platen 22 is, therefore unexpectedly well adapted for use with my uniquely adjustable lower platen and edge guides as described in greater detail below.

It is evident from FIGS. 2 and 3, each pair of bracket members 34a are spaced to admit the insertion of an elevating member 66 which is connected at 68 to distal end of piston rod 70 forming part of an associated cylinder arrangement 72. The piston rod 70 of each cylinder 72 is coupled to the elevating member 66 through a balancing plate 73 and a pair of slide plates 74 which are notched at 77 (FIG. I) to accommodate the pivotal action of the bracket members 34a respectively. Simultaneous actuation of the cylinder 72 raises and lowers the pivot shaft 30 as desired, and with it of course the upper platen 22, relative to the pass lines 42, 44 and the lower platen 24. The upper platen 22 can be raised above and away from the moving strip, after tension is established between adjacent mill stands, by suitable operation of the cylinder 72. Similarly, the lower platen 24 can be lowered beneath the minimum pass line 44 after threading of the mill is completed and tension is established. Thus, neither of the

platens

22, 24 is contacted by the moving strip, and unnecessary wearing of the

platen boards

28, 54 respectively is prevented.

After threading of the strip, the elevating cylinders 72 are deenergized whereupon the balancing plates 73 come to rest upon balance springs 75 (FIGS. 1A and 3A). A pair of balance springs 75 are provided for each plate 73, which can be offset at 73a for engagement with the associated balance springs. The upper platen 22 thus is lowered to a position substantially parallel with the lower platen 24 and is closely spaced from the adjacent segment of moving strip. At the same time the lower platen is lowered to a position just below the lowest pass line 44. The platens then are removed from the moving strip to minimize wear but are closely positioned for quick and effective clamping action during tailing out.

A spring loaded washer 71 or equivalent biased, lostmotion arrangement can be coupled in the junction between each of the piston rods 70 and the associated slide plate 74 to provide a soft clamping action of the strip (not shown) when inserted between the juxtaposed surfaces of the upper and

lower platens

22, 24.

As better shown in FIG. 3 the elevating cylinders 72 for the upper platen 22 are mounted respectively on housings 76 therefore which are spanned by stabilizing plate 78 for structural rigidity. In the illustrated arrangement an air cylinder 80 is pivoted on brackets 82 mounted on the spanner plate 78. The piston 84 of the air cylinder 80 is pivotally connected to a splash guard 86 which is thereby movable between the

positions

86, 86a thereof as shown in FIG. 1.

An extension plate 88 can be secured to the leading edge of the upper platen 22 by means of a bracket 90. The extension plate 88 thus can be supported by the bracket 90 at an angle to the upper platen 22 to facilitate threading. As in the case of the stern portion 60 of the T-shaped upper platen 22, the width of the extension plate 88 is such as to just fit within the minimum opening of the front edge guides 62 at their positions as denoted by

chain outline

62a, 64a of FIG. 3.

As noted above thelower platen assembly including the platen 24 is pivoted about a pair of stub shafts 56. The pivoted structure including the lower platen 24 must perforce carry with it the unique adjustment mechanism for the front and rear entry guides 62, 64. The unexpected manner in which this is accomplished in accordance with the invention will now be described. In the illustrated arrangement the lower platen support plate 52 is mounted on a pivoted support denoted generally at reference character 92. The support 92 in this arrangement includes platen support plate 52 and lower support plate 96 spaced by sidewalls 98, 100 to form a box-like structure which, together with the lower platen 24 is pivotable about the aforementioned stub shafts 56. The pivoted support structure 92 is secured in this example to the stub shafts 56 by a pair of columnar supports 102, which extend between the platen plate 52 and lower support plate 96.

Each stub shaft 56 is mounted for angular displacement in suitable antifriction means such as sleeve bearing, which 104 in turn is supported in pivot housing 106.

The pivot housings 106 are secured in upstanding fashion from a slidably mounted carriage structure for the entry guide mechanism 20, as denoted generally at 108 and described in greater detail below. The pivot housings 106 protrude through aperatures 110 respectively therefore in the lower supporting plate 96 of the pivot structure 92. Each pivot housing 106 therefore extends generally between the associated columnar support 102 and sidewall 98 of the pivoted support 92. The aperatures 110 are afforded such dimensions as to accomodate relative movement between the pivoted structure 92 and the pivot housing 106 as the lower platen 24 and its pivoted support structure 92 are angularly displaced relative to the pivot housings 106 thereby turning the stub shafts 56 in their bearings 104.

In the illustrated arrangement, the lower platen 24 and associated components are pivoted by means of changing attitudes of the strip (not shown) during the threading operation, or by the tendency of the lower pivoted platen 24 to follow opposed angular displacements of the upper pivoted platen 22 relative to the attitude of the strip when the latter is being threaded.

As better shown in FIG. 5 the pivot housings 106 are rigidly mounted on an upper carriage plate 112 of the slidably mounted carriage 108. Provision is made for sliding or otherwise moving the carriage 108 in a plane more or less parallel to the pass lines 42, 44 and in a direction toward and away from the work rolls 46 or 48. Withdrawal of the carriage 108, and with it the lower platen 24, greatly facilitates the roll changing operation by removing the rear liner board projection 114 of the lower platen 24from the neighborhood of the work rolls. On the other hand the entire support structure for the lower platen 24 of the entry guide mechanism 20 can be moved toward the work rolls by means of the carriage 108 to facilitate threading the associated mill stand of the rolling mill. In effect this affords an adjustable apron for the threading operation. In furtherance of these purposes a pair of spaced rails 116 (FIG. 3) are mounted on the associated mill housings or other suitable support (not shown) of the mill adjacent the rolling mill stand 118. The carriage plate 112, which is spaced sufficiently below the lower supporting plate 96 of the lower platen 24 to admit of pivotable movements thereof, is provided at each lateral edge of the carriage plate 112 with horizontal and

vertical slide plates

119 and 120 for engaging each of the slide rails 116. Adjacent each of the rails 116, an inward and upstanding guide plate 122 is depended from the carriage plate 112 to back up the associated slide plates 120 and to support a pair of hold down

rollers

124 or 126.

Also depending from the carriage plate 112 are a pair of hydraulic,slide actuating

cylinders

128, 130. Each of the cylinders 128, is pivotally mounted on a pair of

bracket members

132, 134 likewise depending from the underside of the carriage plate 122 (FIG. 3). As better shown in FIG. 1 a distal end of each cylinder piston rod is pivotally secured to a stop 136 at the rearward end of the associated rail'116. Conduit connections (not shown) can be made to the

cylinders

128, 130 and to other actuating cylinders of the entry guide mechanism 20 for actuation in the usual manner.

Returning once again to the edge guides 62, 64 and in greater detail, the illustrated arrangement of these edge guides permits the incoming or head portion of the strip to be squared up bythe two pairs of edge guides 62, 64 (FIGS. 2, 6) preparatory to feeding to the work rolls 46 or 48. Each of the edge guides 62 or 64 includes in this example a pair of rollers 138 which re disposed normally of the bottom platen 24 for simultaneous engagement with the adjacent edge of the strip (not shown). The rollers 138 of each edge guide are rotatably mounted in a slidable support structure 140 which includes a more or less horizontal section 142 flushly mounted in the lower platen 24. The support structures for the front edge guides 62 include upper, beveled extensions 144 which, along with the front extension 88 of the upper platen 22, facilitate threading the leading edge of the strip into the entry guide mechanism 20.

The horizontal support sections 142 are slidably mounted as best shown in FIG. 1 on the platen plate 52 and are likewise provided with liner boards 146 which are substantially flush with the liner boards 54 on the lower platen 24. In this way each pair of edge guides 62, 64 can be advanced or withdrawn relative to one another between their solid outline positions 62, 64 (FIG. 3) and their

chain outline position

62a, 64a. In consequence any width of strip within the limits imposed by the maximum and minimum positions of the edge guides 62, 64 of the entry guide mechanism can be accommodated in a squared-up position relative to the

work roll

46 or 48. In furtherance of edge guide slidable supports 140 can be moved along transversely extending slots 148 in the lower platen 24.

At a position below the lower platen supporting plate 52 each of the edge guides 62 or 64 is provided with a downward extension 150 or 152. In the arrangement illustrated, particularly with downward extensions 150 to which are secured transversely extending actuation bars 154 having racks 156 thereon. The slide bars 154 are supported at an upper elevation, as better shown in FIGS. 1 & 3. The remaining edge guide 62 (FIG. 3) is connected through its downward extension 152 to the barrel of a movable cylinder 158 provided with a similar rack 160 thereon. A distal end of piston rod 162 is pivotally connected at 164 to side wall 98 of the pivotable housing or support 92 for the lower platen 24. The other or left-hand edge guide 64 if slide bar 155 supported at a lower elevation (FIG. 1) and having rack 157.

The cylinder rack 160 and the rack 157 of the lower slide bar 155 each engage respectively associated pinions 166, 168 which are rigidly secured to shaft 170, which is rotatably mounted adjacent its ends on sidewalls 100 of the tiltable lower platen support 92. Each of the upper slide bars 154 of the right-hand edge guides 62, 64 of FIG. 2 in turn are engaged with the pinions 166, 168 respectively. Accordingly rotation of the shaft 170 and the pinions 166, 168 rigidly secured thereto causes each pair of

racks

156, 160, and 156, 157 to advance or withdraw from one another depend ing upon the direction of shaft rotation. Slots 153 (FIG. 4) are provided in the left-hand edge guides 62, 64 to accommodate passage of the upper slide bars 154.

The driving means for such rotation is supplied by generally horizontal movement of the rack 160 affixed to the parallel of the cylinder 158 or other suitable linear drive. Thus by advancing and withdrawing the moveable cylinder 158 along its piston rod 162, the associated edge guide 162 (FIG. 3) is similarly moved along its slot 148, and simultaneously the shaft 170 is rotated. The remaining

racks

156, 157 and the associated lower slide bar 155 and the two upper slide bars 156 are thus slaved through the described or equivalent linkages to movements of the cylinder 158 along its piston rod 162. Each pair of edge guides 62 or 64 are accordingly advanced or withdrawn relative to one another through identical distances such that the two pairs of edge guides are always squared-up relative to the lower platen 24, irrespective of the width of strip accommodated thereby.

As noted previously, the pivotable lower platen 24 can be lowered to a position in this case below the minimum pass line 44 such that the platen 24 is closely displaced from the moving strip upon reestablishment of tension in the rolling mill until clamping of the strip is necessitated during tailing-out. In further accord with the invention, both

platens

22, 24 are closely spaced from and generally parallel to the moving strip. When tail-out clamping is required both

platens

22, 24 are moved toward the strip for clamping engagement. This avoids setting up any vibratory or other transverse motion in the strip which would interfere with efficient clamping. Such elevation of the lower platen 24 for clamping engagement with the underside of the strip is best accomplished by elevating the entire support housing 92 including the platen 24 supported thereon, the edge guides 62, 64, the pivotal mechanism for the lower platen 24, and the adjustment mechanism for the edge guides. Elevation of the lower platen 24, therefore, does not interfere further with the normal operation of these components. The strip tension is such that both

platens

22, 24 readily assume the attitude of the adjacent strip segment when the platens are both moved into clamping engagement therewith.

In the illustrated arrangement, such elevating means are unexpectedly but most conveniently associated with the pivot housings 106 for the stub shafts 56 on which the pivotable housing structure 92 is supported. In furtherance of this purpose each pivot housing 106 includes a bearing support and slide member 172 slidably mounted in the pivot housing 106 as better shown in FIGS. 5 & 6, and each bearing support 172 carries with it the associated sleeve bearing 104 and stub shaft 56. Each of the bearing supports 172 is constructed as a modified cylinder having an elongated bearing end in which the sleeve bearing 104 and stub shaft 56 are inserted. A plunger 174 is reciprocatably mounted in each of the slide members 172 and protrudes therefrom to engage the upper surface (FIG. 5) of the carriage plate 1 12. By suitably pressurizing the cylinder portions of the slide members 172 the latter can be elevated within the limits imposed by their cylinder portions. Such elevation similarly elevates the stub shafts 56 carrying with them he housing structure 92 supported thereon and the lower platen 24. By thus elevating the stub shafts 56, the support housing 92 and the lower platen 24 are free to pivot within the limits imposed by the entry guides mechanism 20 irrespective of the elevated position of the lower platen 24. Such pivoting and elevation are likewise independent of the particular position of the slide carriage 108 along its rails 116. Most importantly, the

edge guide

62, 64 of the lower platen 24 can be adjusted between their limit positions (FIG. 3) irrespective of the pivoted or elevated position of the lower platen 24 or the longitudinal position of the slide carriage 108.

From the foregoing it will be apparent that novel and efficient forms of Strip Mill Entry Guides have been described herein. While certain presently preferred embodiments of the invention and presently preferred methods of practicing the same have been shown and described herein, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the spirit and scope of the invention.

What is claimed as new is:

1. An entry guide mechanism comprising upper and lower platens positioned to receive an elongated workpiece therebetween, a support pivotally secured to said upper platen for pivotally supporting said upper platen, a separate support pivotally secured to said lower platen for pivotally mounting said lower platen independently of said upper platen, and a drive mechanism secured to at least one of said supports to elevate at least one of said platens toward the other to clamp said workpiece therebetween, the pivotal mountings for said platens conforming the attitudes thereof with that of a juxtaposed segment of said workpiece.

2. The combination according to claim 1 wherein an elevating mechanism is provided for each of said platens to facilitate said clamping and to conform said platens to differing pass lines of said workpiece and to withdraw said platens from said pass lines when said workpiece is supported independently thereat.

3. The combination according to claim 2 wherein a pair of said elevating mechanisms are so coupled respectively to the pivoted supports for said platens that each of said platens can be pivoted substantially independently of said elevating mechanisms.

4. The combination according to claim 1 wherein one of said platens is provided with edge guide mechanisms transversely slidably mounted thereon for engaging and guiding the lateral edges respectively of differing widths of an workpiece.

5. The combination according to claim 4 wherein two juxtaposed pairs of said edge guides are so mounted on said one platen for squaring-up said workpiece relative to said entry guide mechanism.

6. The combination according to claim 5 wherein a drive mechanism is coupled to each of said edge guides for simultaneously withdrawing and advancing each of said pairs of edge guides relative to one another.

7. The combination according to claim 6 wherein said drive mechanism includes a prime mover coupled to one of said edge guides for so advancing and withdrawing one edge guide, the remainder of said edge being slaved to said one edge guide through respective connective linkages.

8. The combination according to claim 7 wherein said prime mover is a linear motor having an elongated rack thereon and said connective linkages include slide racks respectively coupled to said remainder edge guides, pairs of said racks being respectively juxtaposed and enmeshed with a pinion shaft rotatably mounted on said lower platen.

9. The combination according to claim 1 wherein the pivot support for said lower platen is mounted on a carriage forming part of said entry guide mechanism and movable longitudinally of said workpiece.

10. The combination according to claim 9 wherein an elevating mechanism for said lower platen is mounted on one of said carriage and said lower platen pivoted support for raising and lowering said lower platen pivot support relative to said carriage for elevating said lower platen.

11. The combination according to claim 4 wherein the other of said platens is provided with at least one extension shaped for insertions between said edge at a minimum opening therebetween.

12. The combination according to claim 1 wherein an elevating mechanism is coupled to said upper platen pivoted support for elevating said upper platen and its support, said elevating mechanism being coupled to said upper platen support through a biased lost-motion arrangement for a soft-clamping of said workpiece between said platens.

13. The combination according to claim 1 wherein at least one of said pivotally mounted supports includes a pivot shaft extending transversely of the associated platen and coupled to said drive mechanism, and motion regulating means are coupled to each end of said pivot shaft to ensure elevation of said associated platen without canting transversely of said workpiece.

14. The combination according to claim 1 wherein a stop member is secured to said one support for determining with the other of said platens a funnel disposition of said associated platen at an upper elevated position thereof, and biasing means are coupled between said associated platen and said support for biasing said associated platen to a position generally parallel with said elongated member upon removal of said associated platen from said stop member.

15. The combination according to claim 14 wherein resilient support means are provided on said one support for resiliently engaging opposed end portions of said associated platen for determining a running attitude of said associated platen at a position closely adjacent said workpiece but spaced therefrom.

16. The combination according to claim 1 wherein said drive mechanism includes angular displacement means coupled to at least one of said pivoted supports for pivoting juxtaposed portions of said platens toward one another for clamping purposes.

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