Apparatus for Cutting Corrugated Strip Stock at Variable Lengths

The present invention is directed to machines for corrugating a continuous length of strip stock to form heat exchanger strips or the like, and more particularly to severing of the continuous strip stock into individual strip lengths.

Apparatus for manufacture of metalic strips having corrugations extending transversely of strip length are disclosed in U.S. Pat. Nos. 3,998,600, 4,067,219, 4,268,568 and 4,507,948. In general, a continuous length of ribbon or strip stock is fed from a stock coil between one or more pairs of opposed rollers having intermeshing teeth for forming corrugations or fins in the strip stock passing therebetween. The corrugated stock is then fed to a cutting or severing station at which motion of the strip is arrested and the strip is cut to individual lengths. A takeup roller arrangement is positioned between the forming rollers and the cutting station to permit continuous operation of the forming rollers while advancement of the corrugated stock is arrested for cutting. In U.S. Pat. No. 4,507,948, the cutting station comprises a roller having slots formed in the periphery thereof, and a rotary saw blade positioned on the opposite side of the strip stock path. Position sensors detect location of a roller slot opposite the saw blade, at which point motion of the strip stock is arrested, and the saw blade is moved into the opposing roller slot so as to sever the strip stock captured therebetween. Severed strip stock length is thus determined by diameter of the slotted roller and position of the slots and sensors. Any variation in severed stock length requires major readjustment of the forming line and/or replacement of individual components in the line.

It is therefore an object of the present invention to provide a machine of the described character for corrugating a continuous length of strip stock that includes facility for convenient and rapid adjustment of severed stock lengths. Another object of the present invention is to provide a machine of the described character in which severed stock length may be selectively varied during machine operation.

Another important object of the present invention is to provide an improved cutting apparatus, as compared with the saw blade and slotted-roller arrangement of the prior art as described above.

Yet another object of the invention is to provide a machine of the described character for corrugating two continuous lengths of strip stock, for severing such strip stocks at continuously and independently controllable lengths, and for stacking the severed strip lengths so that the stack is of a contour for use in heat exchangers, catalytic convertors and like apparatus of predetermined peripheral geometry. Another more specific object of the invention is to provide a dual strip machine of the described character that is compact in construction, and that occupies about the same shop floor space as do single-strip machines of the prior art.

Yet another object of the present invention is to provide a machine for corrugating continuous lengths of strip stock that satisfies one or more of the foregoing objectives, and yet is economical to fabricate, readily implementable by way of retrofit in corrugation machines previously constructed, and fully automatic in operation.

The present invention thus contemplates a machine for corrugating one or more continuous lengths of strip stock that includes facility for feeding a continuous length of strip stock between opposed corrugation rollers, and a cutting station positioned to receive the continuous length of corrugated stock from the forming rollers for cutting such corrugated stock into individual stock lengths. In accordance with a first important aspect of the present invention, apparatus for controlling individual strip stock lengths includes a sensor positioned to engage the corrugated strip stock between the forming rollers and the cutting station for measuring running length of corrugated stock fed to the cutting station, and a control mechanism responsive to measured running stock length for energizing the cutting station when running length equals a predetermined or preset length. In the preferred embodiment of the invention, the length-control system includes a programmable controller or the like having facility for receiving and storing a programmed sequence of stock lengths, and for comparing measured running lengths in turn to each of the preprogrammed stock lengths in the sequence. The running length measurement sensor in the preferred embodiment of the invention comprises a roller having teeth positioned to engage corrugations in the continuous length of corrugated stock and a sensor responsive to rotation of the roller for measuring running stock length. Most preferably, the length-measurement roller is coupled to a motor, which in turn is coupled to the controller for arresting travel of the corrugated stock to the cutting station and activating the cutter when such travel is arrested. Thus, the measurement roller in the preferred embodiment of the invention serves the dual functions of selectively feeding and arresting motion of the corrugated stock strip to the cutting station, and measuring running length of the corrugated strip fed to the cutting station.

In accordance with a second aspect of the present invention, the cutting station comprises a plate having a slot for receiving the continuous running length of corrugated stock, a shear knife or blade positioned adjacent to the slot and mounted for motion on the plate transversely of the slot, and a blade drive mechanism coupled to the controller for selectively reciprocating the shear blade over the stationary plate so as to engage and sever stock extending through the plate slot. In the preferred embodiment of the invention, the shear blade forms an integral part of a shear plate resiliently urged against a flat bearing surface on the stationary plate and guided by rollers carried by the stationary plate for controlled motion transverse to the axis of the plate slot. The shear-drive mechanism in the preferred embodiment of the invention comprises an electric motor selectively energizable by the machine controller. The motor is coupled to the shear plate through a cycloidal drive mechanism for controlled acceleration, velocity and deceleration during motion of the shear blade.

In accordance with yet another aspect or feature of the present invention, the forming machine includes first and second independently controllable forming lines with separate stock feeding and corrugating stations positioned in vertically superimposed relationship such that the continuous corrugated strip lengths are vertically spaced and superimposed at a common cutting station. The cutting station preferably includes a stationary plate as previously described having vertically spaced horizontally oriented strip-receiving slots. The shear plate has a pair of integral horizontally-oriented blades respectively positioned adjacent to the associated slots, so that activation of the shear plate simultaneously severs lengths of stock from both the first and second strips. The severed strip lengths thus fall by gravity and are automatically stacked beneath the cutting station. Most preferably, the first and second machine lines include facility for forming corrugations of differing pitch and height, and each line includes facility for independently measuring and controlling severed strip lengths in respective preprogrammed sequences as previously described.

The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a schematic diagram of a strip corrugation machine in accordance with a presently preferred embodiment of the invention;

FIG. 2 is a schematic diagram of a stack of severed corrugated stock lengths obtained in operation of the machine of FIG. 1;

FIG. 3 is a fragmentary functional block diagram illustrating the severed strip length-control feature implemented in the embodiment of FIG. 1;

FIG. 4 is a fragmentary sectional view in side elevation of the stock cutting or severing station in the preferred embodiment of the invention illustrated in FIG. 1;

FIG. 5 is an end elevational view of the cutting station illustrated in FIG. 4; and

FIG. 6 is a fragmentary sectional view taking substantially along the line 6--6 in FIG. 5.

FIG. 1 illustrates a machine 10 for corrugating continuous lengths of strip stock as comprising first and second vertically spaced and superimposed forming lines 12, 14. Line 12 includes a coil or roll 16 of strip stock suitably mounted and driven by a motor 18 for feeding a continuous length of strip stock 20 over a roller carried by a dancer arm mechanism 22, over an idler roller 24 and through a strip tensioning station 26 to a corrugating station that includes opposed pairs of corrugating rollers 28, 30, and 32, 34. Rollers 28, 32 are jointly driven by a motor 36 for forming a continuing series of transverse fins or corrugations in stock 20, with corrugation pitch and height being determined by contour of and separation between the forming rollers, tension applied at station 26, strip speed and other variables. A motion sensor, preferably a resolver, is coupled to motor 36.

The continuous length of corrugated strip stock is fed over a series of rollers at a slack take-up station 38, and thence to a cutting station 40. A height gauge 42 is positioned between take-up station 38 and cutting station 40 for measuring height of corrugations formed in strip stock 20, and for feeding an appropriate height-measurement signal to a machine controller 44. A pair of rollers 46, 48 oppositely engage the corrugated strip stock downstream of height gauge 42--i.e., between height gauge 42 and cutting station 40. Roller 46 is driven by a motor 50, which in turn is coupled to controller 44 for selectively arresting motion of the strip stock during a severing operation at cutting station 40. Motors 18, 36 are likewise coupled to controller 44. A motion sensor 52, preferably a resolver, is coupled to motor 18 for supplying signals to controller 44 as a function of velocity of rotation of motor 18 and coil 16. Dancer arm mechanism 22 includes a rotary position sensor for feeding signals to controller 44 as a function of dancer arm position. Tension mechanism 26 includes a clutch driven by controller 44 for selectively and controllably applying tension to strip stock 20 passing therethrough, and a sensor for feeding back to controller 44 a signal indicative of tension actually applied to the strip stock.

To the extent thus far described, corrugation line 12 is substantially as disclosed in U.S. Pat. Nos. 4,507,948 and 4,753,096, and in copending U.S. application Ser. No. 180,174 filed Apr. 11, 1988, all of which are assigned to the assignee hereof and the disclosures of which are incorporated herein by reference. U.S. Pat. No. 4,753,096 discloses in detail that feature of line 12 embodied in height gauge 42, controller 44 and tension station 26 for automatically monitoring height of corrugations formed by rollers 28-34 and controlling such height as a function of tension applied to strip stock 20 upstream of the forming rollers The noted copending application is directed in particular to that feature of line 12 embodied in controller 44, dancer arm 22, coil drive motor 18 and sensor 52, and corrugation roller motor 36 and sensor 37 for driving coil 16 as a function of overall machine speed. Strip-forming line 14 is substantially identical to line 12, and corresponding elements in lines 12 and 14 are indicated by identical reference numerals in FIG. 1 for purposes of convenience and clarity. It will be understood, however, that the measurement and control variables thus far described in conjunction with line 12 are independently variable and controllable by controller 44 in line 14 .

In accordance with the first important feature of the present invention summarized above, lengths of corrugated strip stock severed at cutting station 40 are individually measured and controlled in each machine line 12, 14. Specifically, a rotary position sensor 54, preferably a resolver, is coupled to each motor 50 for feeding signals to controller 44 as a function of rotation of the associated rollers 46. Rollers 46 preferably comprise gears having teeth which engage and intermesh with corrugations in strip stock passing therepast, so that rotation of rollers 46 and resolvers 54 provide to controller 44 accurate measurements of running strip stock lengths. As shown in FIG. 3, controller 44 preferably includes an operator input mechanism 56, such as an alphanumeric keypad or the like, for entering data into the memory 58 of the controller, and microprocessor-based control circuitry 60 having substantial associated memory 58 and suitable programming for implementing all of the control functions herein described.

Specifically, memory 58 includes facility for storing a sequence of desired stock lengths preprogrammable through input 56 independently for each machine line 12, 14. Control circuitry 60 includes corresponding facility for comparing running lengths of corrugated strip stock fed to cutting station 40, as measured by resolvers 54 and rollers 46, and for arresting motion at motors 50 and activating cutting station 40 (common to both lines 12, 14 as illustrated in FIG. 1) when lengths of corrugated strip stock fed to the cutting station in each line correspond to the preprogrammed lengths stored in sequence at memory 58. Thus, as previously noted, corrugated stock length is measured in each line 12, 14, and the cutting or severing operation is controlled, for selectively and variably obtaining severed stock sections of any length and sequence. It will thus be appreciated in accordance with an important advantage of the preferred embodiment of the invention that rollers 46 serve the dual purpose of feeding and arresting corrugated strip stock to the cutting station, and also of measuring running corrugated stock length through sensors 54.

In accordance with a second important aspect of the present invention summarized above, cutting station 40, which is illustrated schematically in FIG. 1 and in greater detail in FIGS. 4-6, comprises a plate 60 stationarily positioned at the end of each forming line 12, 14, preferably in vertical orientation perpendicular to the generally horizontal planes of running lengths of corrugated strip stock fed to the cutting station. Stationary plate 60 includes a pair of vertically spaced slots 62, 64 having longitudinal dimensions extending transversely of the respective forming lines, and being dimensioned and positioned to receive corrugated strip stock fed therethrough by respective rollers 46, 48 (FIG. 1). A shear plate 66 slideably engages the flat bearing surface 68 of a plate 70 affixed to the outboard face 72 of stationary plate 60. Shear plate 66 has a pair of slots 76, 78 which normally register with slots 62, 64 in stationary plate 60. The beveled lower edges 80, 82 (FIGS. 4 and 5) of shear plate slots 76, 78 form shearing edges for severing engagement with strip stock in stationary plates slots 62, 64 when shear plate 66 is driven upwardly (in the orientation of FIGS. 1, 4 and 5). For driving purposes, shear plate 66 is coupled to a drive motor 84 (FIGS. 1 and 4) through an eccentric cycloidal drive mechanism 86.

A pair of arms 88, 90 are mounted by respective pivot pins 92, 94 to stanchions 96, 98 upstanding from the outboard or downstream face of stationary plate 60 laterally outwardly or respective side edges 124 of shear plate 66. Each arm 88, 90 is generally T-shaped as viewed in end elevation (FIG. 5), and carries a pair of vertically spaced roller bearings 100 fastened at the free ends of arms 88, 90 by the bolts 102 and the nuts 104. A pair of studs 106 are adjustably threadably received on stationary plate 60 laterally outwardly of shear plate side edges 124, and are affixed to plate 60 by the jam nuts 108 (FIG. 6). Each stud 106 extends outwardly from stationary plate 60 through an aperture 110 (FIG. 6) centrally positioned in associated arm 88, 90. A coil spring 112 is captured in compression around each stud 106 between a first washer 116 and a second washer 114 that engages the outboard surface of the associated arm 88, 90. A pair of jam nuts 118 are threaded onto each stud 106 outwardly of washer 116 for selectively adjusting compressive forces of springs 112. Roller bearings 100 engage the outboard face of shear plate 66 adjacent to the lateral side edges thereof, so that the several springs 112 collectively urge shear plate 66 against bearing surface 68. Two pair of roller bearings 120 are affixed by suitable screws 122 to stationary plate 60 laterally outwardly of shear plate 66 and engage parallel side edges 124 of the shear plate for guiding vertical motion of the shear plate as driven by motor 84 and cycloidal drive 86.

Thus, in accordance with this feature of the present invention, corrugated stock lengths are simultaneously severed in both of the forming lines 12, 14. Such stock lengths fall by gravity onto a collection surface 126 (FIG. 2) so as to be automatically stacked. In the example of FIG. 2, the corrugated stock lengths 20a formed in line 44 have convolutions of lesser height and pitch as compared with the stock lengths 20b formed in line 12. Likewise, as previously noted, stock lengths may be controlled in any desired sequence, so that in the example of FIG. 2, the first pair of stock lengths on collection surface 126 are of longer dimension than are the second pair of stock lengths. Thus, the length-wise contour of the stack of stock lengths may be controlled to correspond with any desired peripheral contour of the structure into which the stock lengths are to be mounted in a later operation.

There has thus been described a preferred embodiment of the present invention which embodies several aspects or features which advantageously function individually and in cooperation to satisfy all of the objects and aims previously set forth.