Patent Publication Number: US-6339947-B1

Title: Rotary apparatus with moveable die

Description:
This application is a continuation of copending U.S. Application Ser. No. 09/132,019, filed Aug. 10, 1998, now U.S. Pat. No. 5,983,693, as a division of U.S. Application Ser. No. 08/403,732, filed Mar. 15, 1995, now U.S. Pat. No. 5,791,185. 
    
    
     TECHNICAL FIELD 
     The invention relates to rotary apparatus for performing a variety of functions on a moving workpiece. The workpiece may be a continuous strip, or may be a series of separate strips, which move continuously through the rotary apparatus. The material in many cases will be strip steel, but the invention is of much wider application. 
     BACKGROUND ART 
     Rotary apparatus for performing a variety of functions on continuous strip material such as strip steel, have been proposed over the last at least fifty years. However, a need has remained for a rotary apparatus to satisfactorily perform precise functions on a moving strip. There are necessarily upper and lower rotary devices which register with one another and they carry respective upper and lower rotary dies. It is well known in all die forming operations that the two dies must register precisely with one another on opposite sides of the workpiece before they close. It is for this that most of the earlier proposals have not been successful. No way was known to achieve a satisfactory form of precise registration of each pair of dies. 
     However, in U.S. Pat. No. 5,040,397 of Ernest R. Bodnar, Rotary Apparatus granted Aug. 20, 1991, there is shown a form of rotary apparatus, in which upper and lower rotary devices carried semi-rotary die carriers. The die carriers were themselves guided by guide pins. The guide pins rode in cam tracks. The guide pins were located in pairs, one at each end, of each of the semi-rotary devices, and the guide cams were located at opposite ends of the rotary devices. 
     By offsetting one of the guide pins at one end relative to the guide pin at the other end, and also by precisely profiling the guide cams at each end of each of the rotary devices, it was possible to bring the semi-rotary die supports into precise registration just prior to closing, and during closing, and just after closing on the workpiece. This proposal has proved to be satisfactory for many applications. An improvement to the above described apparatus of U.S. Pat. No. 5,040,397 is described in Canadian Patent Application No. 2,066,803. In that patent application, the inventor, Ernest R. Bodnar, describes the provision of guide pins on each of the semi-rotary die supports. By offsetting respective forward and rearward guide pins on respective guide supports, and by providing two separate guide cams at each end of the rotary apparatus, it then became possible to provide for all four pins to engage respective guide cams just prior to closing, during closing, and just after closing. This proposal may produce a much improved degree of registration between the respective dies carried on the die support. This is particularly important in heavier duty applications, or in applications where the line speed was desired to be increased. Even in this system however there were limitations. For example, it will be understood from a simple geometrical analysis that whereas two dies may register with one another just prior to closing, and during closing and after closing, they are in fact traversing arcs of a circle, as the rotary supports rotate. 
     This means that the linear speed of the die was greatest at the point where the two dies closed, and was somewhat reduced just prior to closing and just after closing. 
     On the other hand, since the dies are required to perform operations on a flat workpiece, whether a continuous strip, or discontinuous strip pieces, it will be apparent that there is a very slight degree of “mismatch” in speed of forward movement as between the pair of dies, and the workpiece between them just before closing and just after closing. Precise speed matching is achieved only at the point where the dies are fully closed on the workpiece and the planes of the two dies are precisely tangential to each other. 
     In operations where relatively thin workpieces were being treated, or where relatively shallow formations were being formed, this slight degree of mismatch in speed did not produce any serious consequences. However, it is desirable to apply this technology to a wider range of products. It is desirable to apply this technology to products having a greater physical thickness than relatively thin sheet metal workpieces, and it is also desirable to apply this technology to the drawing of deeper formations in the workpiece. 
     In both of these cases, it is apparent that the contact time period during which the two dies are in contact with the workpiece will be somewhat increased as compared to working on thin sheet workpieces such as thin sheet metal and/or drawing relatively shallow formations. In these cases, any degree of mismatch in linear speed between the workpiece itself, and the two dies becomes much more significant. 
     Accordingly, it is desirable to provide in the first place a method of accommodating the mismatch in speed occurring between the dies moving around a rotary arc, and the workpiece moving along a linear path. 
     A further problem however relates to the design of the rotary apparatus itself. 
     In the above noted U.S. patent, and the development thereof described above, herein termed the “two pin rotary”, and the “four pin rotary” respectively, the circumferential path around which the die itself could pass was determined by the circumferential path around which the semi-rotary die supports themselves could pass. This meant that if it was desired to increase the size and particularly the depth, of the dies, the entire design of the rotary apparatus had to be redesigned to accommodate these variations. 
     This clearly either limited the degree of application of the rotary apparatus or meant that considerable engineering costs were incurred each time the rotary apparatus was designed to handle a particular size and depth of die. 
     Clearly, it is desirable for a more or less standard size of rotary apparatus to be arranged so as to accommodate dies which are themselves of different sizes and in particular in which the dies are of different depths, without being obliged to re-engineer the entire rotary apparatus itself desirably, all that will be required is to place the rotary support devices on centres which are further apart for deeper dies or closer together for shallower dies, and of course, to alter the size and pitch of the gears which interconnect them to ensure that they rotate in unison. This itself is a relatively much simpler task than re-engineering the whole of each pair of the rotary devices themselves. 
     For the purposes of this application, the term “forming” is deemed to incorporate by reference any die operation which may be performed on a workpiece, whether it may be termed in the trade as “embossing” “forming” “drawing” “blanking” “cutting”, or any other operation on a workpiece which is performed by a pair of dies, and wherever used herein the term forming is deemed to incorporate any and all such operations, including those not specifically mentioned above. 
     DISCLOSURE OF THE INVENTION 
     According to the invention, there is provided a rotary apparatus for continuous rotary forming of web workpiece, the apparatus comprising a rotatable first roll unit and corresponding rotatable second roll unit; a first die support member carried by the first roll unit, the first die support member having a leading edge and a trailing edge respective to rotation of the first roll unit; a second die support member carried by the second roll member, the second die support member having a leading edge and a trailing edge respective to rotation of the second roll unit; means for transporting a web workpiece in a forming plane between said first and second roll units; 
     each die support member comprising a first part carried by the respective roll unit and including the leading and trailing edge and a second part having a platen surface for mounting a die, the second part being mounted on the first part for reciprocal motion transverse to the leading and trailing edges. 
     Each first and second die support member may be rotatably received in a longitudinal recess of its respective roll unit, the recess having a concave arcuate bearing surface a complementary to a convex arcuate surface of the first part of the respective die support member, the recess defining a concave section of a cylinder and the first part of the respective die support member defining a complementary convex section of said cylinder. The respective concave and convex sections of said cylinder may be minor sections. 
     Preferably, the first part of each first and second die support member and the second part of the first and second die support members are connected for reciprocal movement with respect to each other through resilient connecting members. Each resilient connecting member may be formed of polyurethane rubber and may be seated in seating recesses in both of the first and second parts. Stop members may be provided to limit the reciprocal motion on one of the first and second parts. 
     Rotation of the first part of the die support member in the recess is controlled by cam means which may include a cam follower on at least one end of the die support member in the region of the leading edge engaging a continuous cam. Suitably the cam means also includes a cam follower on the other end of the die support member in the region of its trailing edge and engaging a continuous cam. 
     Alternatively the cam means may comprise a four pin system including a cam follower on one end of a die support member in the region of a leading edge and engaging a continuous cam, a cam follower on the other end of said die support member in the region of the leading edge and engaging a discontinuous cam, a cam follower on said one end of the die support member in the region of the trailing edge and engaging a discontinuous cam, and a cam follower on the other end of said die support member and engaging a continuous cam. 
     According to the invention there is also provided a rotary apparatus for rotary forming of a web workpiece which apparatus comprises: a rotatable first roll unit and corresponding rotatable second roll unit, said units being connected for synchronous rotation through rotary cycles, each of said units comprising a carrier having a central axis for rotation thereabout; means for transporting a web workpiece between said units in a forming plane at a web speed; means for rotating the first and second roll units at constant opposite rotational speed to have a roll unit tangential peripheral speed at the forming plane similar to the web speed; each roll unit being provided with at least one recess defining a concave minor section of a cylinder having a longitudinal axis parallel with said carrier central axis; a die support member having a leading edge and a trailing edge being rotatably received within said recess, the die support member including a first part having a curved convex surface nested in said recess and defining a similar minor section of said cylinder, the die support member also including a second part projecting out of said recess and said die support member being rotatable about the notional central axis of said cylinder and offset from the first part of the die support member. The first part and the second part of each die support member may be separate one from the other and connectable one to the other. 
     The cam means, as in the previous alternative, may comprise a cam follower on at least one end of the die support member in the region of the leading edge engaging a continuous cam. Again, suitably, the cam means includes a cam follower on the other end of the die support member in the region of its trailing edge and engaging a continuous cam. 
     As before, the cam means may be a four pin system including a cam follower on one end of a die support member in the region of a leading edge and engaging a continuous cam, a cam follower on the other end of said die support member in the region of the leading edge and engaging a discontinuous cam, a cam follower on said one end of the die support member in the region of the trailing edge and engaging a discontinuous cam, and a cam follower on the other end of said die support member and engaging a continuous cam. 
     The cam follower in the region of the leading edge and the cam follower in the region of the trailing edge may be located on end extensions of the die support member, the extensions extending out of the recess and respectively flush with ends of the second part of the die support member. The axles of the die support member may also be located on the extensions. Such a system may provide substantial versatility. For example it may be possible to interchange dies of different depths on the die support member. 
     Each roll unit may suitably include four die support members. 
     Bearing arms may provided for said axles of each die support member, the bearing arms being rotatable on the carrier central axis. 
     The invention further comprises a rotary apparatus wherein a cut to length mechanism is provided upstream of the rotary forming apparatus, whereby the workpiece may be cut into separate plates or pieces, which are then passed successively through the rotary apparatus, in timed relation to the formation of openings, or other formations therein by the rotary apparatus. 
     The invention further comprises such a rotary apparatus, wherein provision may be made for separating one of the rotary units from the other in a pair of rotary units, so that a portion of workpiece may pass therethrough untreated while maintaining the rotation of said moved rotary unit, whereby to maintain the rotation of the two rotary units in timed relation continuously. 
     The various features of novelty which characterize the invention are pointed out with more particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration in perspective of a manufacturing line incorporating rotary apparatus according to the invention; 
     FIG. 2 is an exploded schematic illustration in perspective of a rotary apparatus according to the invention; 
     FIG. 3 is a schematic illustration from an end of the rotary apparatus of FIG. 1; 
     FIG. 4 is an exploded perspective view of the rotary apparatus of FIG. 2; 
     FIG. 5 is a sketch of the comparison of rotary and linear speed of the workpiece and dies respectively; 
     FIG. 6 is an exploded view of a die support member, and platen shoe; 
     FIG. 7 is a view of the platen shoe portion of the die support member showing its connecting surface with the other part of the die support member (the die itself being omitted); 
     FIGS. 8 a ,  8   b ,  8   c  illustrate reciprocal movement of the die support and the die shoe at different stages in operation; 
     FIG. 9 is a sketch of an alternate embodiment of a rotary apparatus set up for feeding cut plate; 
     FIG. 10 is a schematic side view of a roll forming line incorporating the upstream cut to length apparatus illustrated generally in FIG. 9; and, 
     FIG. 11 is a schematic side elevation of a rotary apparatus showing the upstream cut to length apparatus, and also showing the movement of one rotary unit relative to the other. 
    
    
     MODES OF CARRYING OUT THE INVENTION 
     Referring to FIG. 1, there is illustrated a roll  10  of workpiece material web  12  such as metal sheet or plate, e.g. steel plate upon which it is desired to perform various shaping or forming operations. Such operations may typically be performed in a manufacturing line  14 . Web material  12  may be unwound from roll  10  and passed continuously along line  14 , in the direction indicated by arrow A. Alternatively, when material  12  is plate, any other feed may replace roll  10 . The various forming operations are performed on material  12  as it passes different points along line  14 . As material  12  is unwound from roll  10 , typical first operations may be rolling at stations  21  and die forming operations, performed by a rotary apparatus  20  according to the invention. Apparatus  20  may punch holes  22 , or form complex indentations, or both, in material  12  as it passes through apparatus  20 . Subsequent operations may typically include roll-forming operations at station  23 . Further operations as desired may be carried out at station  24 . The final operation is typically the cutting of material  12  in cutting station  26  into standard lengths  28  convenient for further manufacturing or assembly processes and for storage. Stations  23 ,  24 ,  26  are illustrated partly in schematic form. Some stations may incorporate typical longitudinal roll forming dies well known in the art (not shown) and the cut off may in fact be a flying shear well known in the art (not shown) or another set of upper and lower rotary units, with suitable dies. 
     Further nip rollers (not shown) may be used to guide material  12  through stations  23 ,  24  and  26 . Of course, any number of stations  21 ,  23 ,  24  and  26  may be used in sequence, as desired. 
     The above description of a typical manufacturing line is provided herein in order to facilitate the description of the invention. The description of the manufacturing line is not intended to limit the invention in any way. Rather the apparatus according to the invention may be used in any manufacturing line or in any situation requiring high speed, continuous, accurate die forming of strip material. 
     While references made herein to “sheet metal” it will be appreciated that the invention is not limited in any way to the forming of sheet metal. A wide variety of different “materials” may require to be formed, within the generic meaning of that word as defined herein, using the rotary apparatus in accordance with the invention. Such material may be fed from a roll, or may be fed in pieces through the rotary apparatus, and accordingly where used herein the term “strip material” is deemed to include any such material which may be formed in such rotary apparatus, in accordance with the generic use of the term formed as defined herein. 
     Referring to FIG. 2, there is schematically illustrated a rotary apparatus  20  according to the invention. Motor  30  drives upper roll unit  32  in unison with and, at the same speed, as lower roll unit  34  through transmission  35  and shafts  36 . The direction is, however, opposite. The workpiece web  12  passes between and is contacted by upper and lower units  32  and  34 . Upper and lower units  32  and  34  may be supported by suitable bearing means  37 . In this embodiment motor  30  and transmission  35  are such as to provide the outer surfaces of upper and lower units  32  and  34  at the point of contact with material  12  with essentially the same speed as material  12 , so that there is no slippage or relative motion between the material  12  and either or both of upper unit  32  and lower unit  34 . 
     Motor  30 , transmission  35 , and bearings  37  may all be standard components as are well-known in the machine tooling industry. 
     FIG. 3 illustrates in cross-section upper die unit  32  and lower die unit  34  in position to die form sheet material  12 . Upper unit  32  rotates counter-clockwise in the direction indicated by arrow B. Lower unit  34  rotates clockwise in the direction indicated by arrow C. Material  12  moves from left to right in the direction indicated by arrow A. 
     It will be appreciated that the designations “upper”, “lower”, “left” “right”, “clockwise”, and “counter-clockwise” are for convenience of description only and are not intended to limit the invention, which will operate equally effectively in any direction or orientation. Similarly, references to an “upper die” located in a certain position and to a corresponding “lower die” in a certain corresponding position are not intended to limit the invention. upper and lower dies  38  and  40  operate as a pair and the individual location of each is irrelevant to the invention so long as the pair operates together at the required location and time. 
     Upper unit  32  is essentially identical to lower unit  34 . Referring to FIGS. 3 and 4, upper unit  32  includes upper carrier member  41 , which defines a central axis L 1  about which upper unit  32  rotates on shaft  36 . Member  41  defines at least one (in the illustrated embodiment, there are four) recesses or openings  42 , each in the shape of a minor concave section of a cylinder each having a notional axis L 2 . The section extends longitudinally parallel to the central axis L 1  of member  41 . Member  41  further defines abutments  43  between openings  42 . 
     Referring to FIG. 4, the die support members  46  are retained within openings  42  by bearing arms  47  projecting radially from bearing member  45  which is rotatable with the respective upper unit  32  or lower unit  34 . 
     A bearing member  45  is provided to each end of upper and lower units  32 ,  34 . Bearing arms  47  receive stub axles  47 a projecting from each end of die support members  46 , whereby the die support members  46  are retained within recesses  42  but are able to rock within the recesses by rotation of stub axles  47   a  in pivot arms  47 . In fact the axis of rocking of the die support members is coincident with the notional axis L 2  of the cylinder defined by curved surface, but is not coincident with the chordal surface, since the arc of the curved surface is less than 180°. 
     FIG. 5 is a diagram showing the progression of comparative points A 1 , A 2 , A 3  . . . etc. at the rotational surface with points A 1 , B 2 , B 3  . . . etc. of a die. From the projection of points A 1 , A 2 , A 3  . . . etc. onto the web  12  at respective points C 1 , C 2 , C 3  . . . etc, that there is considerable variation of the linear speed component of a point strictly on the rotational surface. Points A 1 , A 2 , A 3  . . . etc. may be translated to points B 1 , B 2 , B 3  . . . etc. by rocking or swinging of rotary member  46   a  in recess  42 , thus advancing the leading edge of the die support member with respect to the surface of rotation. Projection of points B 1 , B 2 , B 3  . . . . etc. onto the web  12  to points D 1 , D 2 , D 3  . . . .etc. respectively show much less variation of the linear component of the compensated rotational speed. 
     Each die-support has a cross-section that is bounded by an arc and chord of a circle. The section is less than 180° of arc so that the rotary member is less than a semi-cylinder. Die support member  46  also comprises a platen die shoe  46   b  connected to the rotary member  46   a . In FIGS. 1 and 3, a first or leading guide pin or cam follower  48  extends from one end of member  46  and a second or trailing guide pin or cam follower  49  extends from the other end member  46 . Guide pins  48  and  49  are mounted on end extensions  50 , attached to opposite ends of rotary member  46   a.    
     As shown in FIG. 3, each die support member defines a leading edge  51  and a trailing edge  52 . 
     The die platens or shoes  46   b  are slidably retained within the die support  46   a  by means of longitudinal edge plates  53  secured to the end walls of the die supports by means of bolts  54  (FIG.  6 ). Plates  53  may engage either the side edges of the platen shoes  46   b , or the side edges of the dies  38 ,  40  themselves. 
     Resilient cushioning members  55  are located in recesses  56  in rotary member  46   a  and in recesses  57  in platen shoes  46   b . These resilient cushioning members  55  may be made of polyurethane rubber. 
     Guide pins  48 ,  49  ensure that the platen shoes  46   b  are located in the desired position. Guide pins  48  and  49  are arranged to engage respective full cams  58  and partial cams  59  as described for example in U.S. Pat. No. 5,040,397, previously referred to. Full cams  58  are offset axially outwardly and partial cams  59  are offset inwardly, in the manner explained in the aforesaid U.S. Patent. In this way cams  58  provide guidance and control around 360°, and cams  59  control each die support from just prior to closing to just after closing of the dies. On a member  46 , pins  48  and  49  define and lie on different axes adjacent leading and trailing edges  51 ,  52 . 
     The platen die shoes  46   b , are thus slidably mounted on support  46 , and are biased centrally by cushioning members  55 . 
     Stub axles  47   a  define axes which are outside the chord of the rotary member  46   a.    
     In FIGS. 2 and 4, leading and trailing pins  48 ,  49  are provided at both ends of member  46 . Upper and lower dies  38 - 40  are mounted on platen shoes  46   b  of members  46  in any conventional manner (eg bolts—not shown). Dies  38 - 40  are mounted on members  46  essentially parallel to the platen shoe  46   b . FIGS. 4 and 6 show dies  38 - 40  and platen shoes  46   b  in foreshortened form so that view of other parts of the die support member may be seen. The shoes  46   b  and dies  38 - 40  are shown in broken lines, in FIG.  4 . 
     An opening  40   a  in the lower (female) die may be provided (FIG. 4) to permit a slug (not shown) to be ejected from the die. 
     Operation of the guide pins  48 ,  49  in conjunction with cams  58  and  59  will now be described. 
     In FIG. 4 leading pins  48  and trailing pins  49  are provided at both ends of each member  46 , and in FIGS. 1 and 3 leading pins are provided at one end and trailing pins at the other end of each member  46 . 
     In FIGS. 2 and 4, leading and trailing pins are shown at both ends. 
     Whatever the manner of providing leading and trailing pins, it is necessary to provide a cam for guiding each set of pins for the proper positioning of the dies  38 - 40 . 
     Where leading pins  48  and trailing pins  49  are provided at both ends of the members  46 , the leading pins  48  may project outwardly of the trailing pins for accessibility to their cam  58  in the region where the die is to engage the workpiece  12  while allowing access of the trailing pins  49  to their cam  59  in the region where the die is to engage the workpiece  12 . It will of course be necessary to adjust the shape of cams  58 ,  59  previously referred to, to engage the respective pins. 
     It will be appreciated that the cam paths  58  and  59  of FIG. 3 may be adapted to the use of pins  48  and  49  at each end of the member  46  by providing cam surfaces only to engage pins  48 ,  49  when the respective die approaches, passes through and leaves the die forming region where exact registration with the cooperating die is necessary. 
     Cams  58  and  59  are provided fixed relative to the axis L 1 . Cams  58  and  59  are shaped and pins  48  and  49  are positioned relative to members  46  whereby the forming planes of dies are essentially parallel to web  12  immediately prior to, during and subsequent to closing. Because each member  46  is each supported by at least two pins on different axes the members may be less prone to rock or otherwise move within their fittings than were those in earlier rotary forming devices. Indeed, when pins  48  and  49  are each provided at both ends of member  46 , then the member is supported stably by four pins. Thus in comparison to previously used rotary devices the clearances required by the cam follower mechanism do not have as great an effect on the accuracy of performing operations. 
     To ensure further accuracy, die registration pins  78  are provided to either side of die  38 . Each registration pin  78  registers with a complementary bore  79  of the cooperating die member  40  of the other unit. Pins  78  and bores  79  are shaped, sized and located on either side of web  12  so that they may cooperate and register with each other without interference with web  12 . As upper and lower units  32  and  34  rotate, register pins  78  on upper dies  38  extend toward and are partially inserted into complementary bores  79  in lower dies  40  prior to contact with web  12 . As dies  38 - 40  come into contact with web  12 , the pins  78  are fully inserted into the bores  79 , thus ensuring the dies contact web  12  in proper registration with each other. 
     In operation upper and lower units  32  and  34  rotate. Each die rotates through the successive illustrated positions of each unit. A closed position of apparatus  20 , which is the position at which web  12  is formed, stamped or otherwise treated is that in which two dies cooperate one with each other for this purpose. It may be regarded as defining the starting point of the rotary cycle. Rotation continues, with each unit rotating to opposite hand. 
     At the starting position web  12  is formed by the upper and lower dies and, as rotation continues upper and lower dies are separated and pins  48  and  49  follow their respective cams  58  and  59 . As rotation continues, the pins  48  cause upper and lower members  46  to swing in their recesses  42  to take up a proper position parallel to each other as they re-approach the starting position. 
     The slidable mounting of the die shoe on the die support member enables the apparatus to compensate for varying actions between the linear web speed and the rotational die speed. 
     This embodiment comprising a rotary die support member  46   a  and a platen shoe  46   b . The shoe is reciprocal with respect to the support transversely to the central carrier axis L 1 . Such transverse movement, i.e. movement along the axis of the web, enables compensation of any discrepancy of speed between rotary units  32  and  36 , and web  12 . The platen shoe,  46   b  may move reciprocally on resilient cushioning members  55  of which two are shown. The members  55  have enlarged ends to limit sliding. The reciprocal motion advances or recedes the platen shoe  46   b  with respect to the rotary motion. 
     Referring to FIGS. 6,  7  and  8 , a die support member  46   a  is connected to a platen shoe  46   b  through resilient members which seat partially in recesses of the rotary member  46   a  and partially in recesses of platen shoe  46   b . Either one of rotary member  46   a  or platen shoe  46  has a H-shaped grease groove  80 . Stop means are also provided. Thus, stop  82  on end extension of rotary member  46   a  co-operates with abutment  84  on platen shoe  46   b.    
     In operation, as dies  38 - 40  approach the forming plane and contact web  12 , platen shoes  46   b  of both upper and lower units  32 ,  34  will be advanced into the position shown in FIG. 8 a . In this position, resilient members  55  are biased and deformed as shown. As dies  38 - 40  exactly pass through the forming plane, the position of FIG. 8 b  is reached. The equalization of the linear component of the rotary speed, and the web speed matches the linear speed of the platen members  46   b , the platen members have slid rearwardly to a median position (FIG. 8 b ). 
     As the dies  38 - 40  leave the forming zone, the linear component of the linear die speed again decreases relative to the web, and the position of FIG. 8 c  is reached. The die shoes are again drawn forwardly to match the web speed, until the dies separate from the workpiece. The die shoes then slide back to their centre, median position. 
     Referring now to FIG. 9, rotary apparatus for forming pre-cut plates is provided. 
     In this case, the rotary forming station is indicated generally by the upper and lower rotary formers  32  and  34 . 
     These rotary formers are representative merely of the leading pair of rotary formers, and there will typically be two or more sets of rotary formers only one being illustrated here for the sake of simplicity. 
     In this embodiment of the invention, the cut-to-length operation is carried out upstream of the rotary formers, so as to cut the strip into separate plates or webs of material each of which is separate from the other. 
     In order to do this, the continuous strip is first of all fed by means represented as strip feed rolls  100 . Typically, these will be feeding a web or strip  12  of material from an uncoiler (not shown) of a type well known in the art, description of which is superfluous. 
     From the strip feed rolls  100  the strip passes over a set of hump roll  102 . The purpose of the hump roll, is to form the strip into a shallow upward curve, the purpose of which will be apparent below. 
     From the hump roll, the strip is then fed between a pair of cut off rolls  104 . Typically, these cut off rolls will be made in the same way as the rotary apparatus described above; that is to say they will have upper and lower roll units, each of which is provided with at least one rotary die support as previously discussed, and the die supports will be controlled by cams in the manner described above. In this case, it may or may not be necessary to provide the sliding relationship between the die shoe and die support described above, again for reasons described. 
     The cut off rolls  104  are normally stationary, and spaced apart a sufficient distance for the strip to pass therethrough. They are operated by any suitable control mechanism indeed generally as control  106  which in turn is connected to a typical digital length measuring device  108  indicated simply as a roll operating on one side or both of the strip. 
     A plate pair of plate stop arms  114  are swingably mounted on a cross shaft  116 , and at their upstream ends  118  are adapted to intercept the leading edge of the plate just before it enters the cut off rolls  104 . 
     The stop arms  114  are connected to an operating arm  120  extending from shaft  116  downstream, adjacent the upper rotary forming unit  32 . 
     At its downstream free end it is provided with a cam roller  122 . 
     The arm  114  is normally held in its upper position by means of the spring and adjustable bolt (not shown). 
     A feed cam plate  124  is mounted on the end of the upper rotary roll unit  32 . cam plate  124  has a plurality, in this case four operating cams  126  spaced apart therearound. The cam plate  124  is secured to the roll unit  32  by means of arcuate slots  128  and adjustable fastening bolts. 
     In this way, the location and orientation of the cam plate relative to the upper roll unit can be adjusted, for precise operation or in cases where the length of the plates cut off the end of the strip are varied from one run to another. 
     In the operation of this embodiment of the invention, strip material is first of all fed by the strip feed rolls to the hump table, where it is formed into a shallow upwardly convex hump. 
     In one mode of operation, the length of the strip material  12  is desired to be cut off to form a plate, or separate web or piece, can be measured by the strip measurement unit  108 . A signal from the strip measurement unit  108  can then signal the control  106  to operate the cut off roll, and to cut off the leading end of the strip at a precise length thereby forming it into a plate or web piece, separate from the strip  12 . 
     The spacing between the cut off rolls  104 , is such that it is generally speaking appropriate to the length of the strip that it is desired to cut off and form into a plate. 
     The leading edge of the strip will already have been intersected by the upstream stop members  118  on the stop arms  114 , so that the strip is momentarily prevented from entering the cut off rolls  104 . 
     Since at this point the strip is temporarily halted, the shallow upward curve of the strip on the hump table will gradually rise. 
     A cam  126  will then depress cam  120  and raise stops  118 . The strip can then pass between the cut off rolls, which are open, and stationary, at this point. 
     The strip advances to the rotary former  32 - 34 , in precisely timed relation to the rotation of the former  32 - 34 . Formations will then be made at precise locations with reference to the leading edge of the strip. 
     The measurement unit  108  will then signal control  106 . The control  106  will then operate the cut off rolls, to cut off the plate to the right length or web to the right length. In this way, the strip or web is cut to a predetermined precise length at predetermined intervals prior to entering the rotary former. 
     This will ensure that the rotary formers will form, and/or emboss and/or blank out the necessary formation in the piece of plate or piece of web, at precise intervals starting from the leading edge of the plate or web piece which is fed from the plate feed rolls. 
     As an alternative to the mechanical cam operation of arms  114 , it be operated by eg a cylinder  129  (shown in phantom), connected to control  106 . Control  106  will then both sense the rotational position of rolls  32 - 34 , operate the cylinder  129  when the rolls are in the correct location for entry of the leading edge of the web. 
     Referring now to a further embodiment of the invention illustrated in FIG. 11, provision may be made, in association with or without the upstream cut to length apparatus described in FIGS. 9 and 10, for the movement of one roll former unit  32 - 34  relative to the other. The purpose of such relative movement is to momentarily permit a portion of the workpiece to pass between the rotary formers, without any rotary formations being formed therein. This may be desirable at the beginning or end of a predetermined length of a workpiece for example for various reasons. 
     As illustrated therefor in FIG. 11, the upstream cut off rolls are indicated generally  104  and the idler roll is indicated generally as  105 . 
     A pair of intermediate feed rolls are indicated as  130 - 130 . 
     A first pair of rotary unit is indicated as  132  and  134  respective. It will be appreciated that a second pair or more pairs of such rotary rolls may be located downstream of the first pair, and would normally be required to operate in the same way as described below, so that the workpiece could pass through each pair of rotary unit, while they are initially open, so that the dies on the respective rotary units will then register precisely with formations already formed at the first pair of rotary units  132 - 134 . 
     In the first pair of rotary units  132 - 134 , the upper rotary unit  132  is movable for example by means of an hydraulic cylinder  136 , between a lower operative position, and upper inoperative position shown in phantom. 
     It is essential that the upper movable roll  132  shall continue to operate in timed relation to the lower roll  134  during such movement, so that when they close once more i.e. when the upper rotary unit  132  is lowered by the cylinder  136 , that the two units are still rotating in unison in a coordinated fashion, with the various dies thereon registering with one another in the manner described above. 
     In this embodiment, this is achieved by means of an idler roll  138 , connecting rolls  130  and  134 , and further downstream feed rolls  140  and  142 . All of these rolls are connected by gear mechanisms of a type well known in the roll forming art, which require no description, so that all of the rolls are rotating in unison in the appropriate directions. 
     The upper downstream feed roll  142  is connected by suitable gearing (not shown) of a type well known in the art to upper movable rotary unit  132 , and since the movement of the upper rotary unit  132  is minimal, possibly no more than an inch or so in extent, the gearing will not become disengaged, as between upper roll  142  and roll  132 , and consequently roll  132  will continue to operate even when it is in its raised position, and when lowered once more will continue to operate in precisely timed relationship with the lower rotary forming roll  134 . 
     The foregoing is a description of a preferred embodiment of the invention which is given here by way of example only. The invention is not to be taken as limited to any of the specific features as described, but comprehends all such variations thereof as come within the scope of the appended claims.