GB1571759A

GB1571759A - Rotary shear machine

Info

Publication number: GB1571759A
Application number: GB9303/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-06-17
Filing date: 1978-03-09
Publication date: 1980-07-16
Also published as: ZA78531B; IE781037L; AU517589B2; AU3301378A; DE2825898C2; IE46924B1; DE2825898A1; JPS547683A; CA1072004A

Description

(54) ROTARY SHEAR MACHINE (71) I, MERRILL DAVID MARTIN, Citizen of the United States of America of 2 Mall Court, Oakland, Alameda County, California, United States of America do hereby declare the invention for which I pray that a Patent may be granted to me and the method by which it is to be performed to be particularly described in and- by the following statement:- A direct drive rotary shear machine is described having helical blades secured to oppositely rotating parallel cylinders for transversely shearing a continuously moving web perpendicular to its direction of travel.

The machine may be controlled for intermittently shearing the web and/or for continuously shearing the web into sheets of predetermined lengths.

Corrugated paperboard is discharged from a corrugator machine as a continuous web which normally travels at substantial velocities. As the web travels, it is operated upon by various machines for conversion into articles of manufacture such as cardboard boxes and the like For economical operation, the machinery manufacturing corrugated paperboard must operate at or near full capacity.

Accordingly, any interruption or slowdown in the production of the corrugated paperboard is detrimental.

An essential machinery unit for manufacturing corrugated paperboard articles is a rotary cutter or rotary shear which severs the travelling paperboard web perpendicular to its direction of travel.

Specifically, it is necessary to transversely sever the travelling web to allow implementaion of order changes downstream. Also, the web must be transversely severed for removal of splice areas. Other reasons for transversely severing the travelling web include removal of sample sheets, removal of web sections which do not meet production criteria, and even diversion of the web into an alternative production machinery line.

Ultimately, of course, the travelling web must be successively severed transversely for production of paperboard sheets or blanks, and in sheet or blank production, it is very important that such cuts be perpendicular relative to the direction of web travel.

The principal disadvantages of existing rotary shear and cutter machinery are as follows: 1) Straight knives are used for severing the web and consequently the entire web must be severed in a single simultaneous cut across its entire width; 2) Straight knives require extremely massive carrier shafts or knife bars in order to withstand the impulse load of a single simultaneous cut across the entire web width; 3) Existing rotary shears/cutters require complex mechanical drives and transmissions for cyclically driving the massive knife shafts which must be capable of withstanding the considerable stresses experienced in so driving such massive knife shafts; 4) The mechanical drives and transmissions must include mechanical means for adjusting the cyclic rotation period of the knife shafts to allow production of sheets or blanks of different lengths;; 5) The range of sheet length which can be cut without decreasing web velocity is limited 6) Existing rotary shears/cutters are inertially limited to operate at low, web velocities (less than 550 f.p.m.) because of their massive components (transmissions and knife shafts).

For additional discussion of other problems and disadvantages of conventional straight knife mechanically controlled rotary shears/cutters see U.S. Patent Nos: 3,748,865 (R.C. Johnson) and 3,003,380 (H. W. Moser), each describing very complex mechanical means for delivering power to the rotating knife shafts and controlling the cyclic rotational period of such shafts.

The most serious disadvantage of existing rotary shear/cutter machinery relates to the short lifetime, i.e. the mechanical vulnerability of its component parts.

Such mechanical vulnerability is primarily due to the massive nature of the components, cyclic loading of gear trains and the impact loading experienced by the components upon each cut or shear. On the average, a conventional rotary shear/cutter must have one or another of its major components repaired or replaced every year. Specific components which are prone to mechanical failure in existing rotary shears/cutters are the transmission drives with sliding cranks and the like.

Counterbalanced cutoff drives, while eliminating many of the problems inherent in sliding crank cutoff drives, introduce additional mass to the drive assembly which must be rotationally driven, thus creating additional inertial limitations on the operation and control of such machines.

Additionally, rotary shear/cutter machines designed for sheet production cannot be used for intermittent cuts, just as rotary shear/cutter machines designed for intermittent cuts cannot be used for sheet production. For example, U.S. Patent No.

3,880,033 (Taylor) describes a rotary cutter assembly designed for intermittently cutting a paperboard web in which a conventional clutch mechanism is utilized to couple the knife bar for rotation thereby precluding accurate control over the length of sheet cut.

Finally, most other machinery units necessary for manufacturing paperboard have capacities to operate at much higher web velocities than existing rotary shears and cutters. In fact, it is often necessary, because of the mechanical vulnerability of existing rotary shears and cutters, to operate machines both up and downstream from the cutter at less than half their operational capacity.

A direct drive rotary shear machine is described having helical cutting blades secured to oppositely rotating hollow cylinders for transversely shearing a continuously moving web of material perpendicular to its direction of travel. A direct current (DC) electrical motor directly drives the oppositely rotating hollow cylinders carrying the helical cutting blades, the cylinders being coupled by antibacklash gearing per my teachings in U.S. Patent No. 3,037,396. The antibacklash gearing maintains precise shearing engagement of the helical blades carried by the oppositely rotating cylinders and minimizes torsional flexure of both the rotating hollow cylinders and the frame structure.

The helical configuration of the blades or knives minimizes loading on the shafts carrying the oppositely rotating cylinders in that the travelling web is severed gradually and progressively as the hollow blade cylinders rotate. The axes of the oppositely rotating cylinders are inclined slightly off square with the direction of travel of the web at an angle equal to the angle which the helical blades bear to the longitudinal axes of the cylinders to enable the machine to sever the web perpendicular to its direction of travel.

A particularly novel aspect of the described rotary shear machine is its rigidity which is provided by the combination of coupled cantilever support bearing frames at the respective ends of the shafts carrying the oppositely rotating cylinders and concrete filled frame and base members.

The coupled external cantilever support bearing frames minimize bending flexure of the oppositely rotating cylinders while the concrete filled frame and base members minimize bending flexure of the frame structure. The concrete filled frame and base members also damp mechanical vibration and minimize the effect of thermal stresses.

Another novel aspect of the described rotary shear assembly relates to means for determining and regulating the rotational period of the oppositely rotating cylinders by controlling the motor directly driving the cylinders, thus eliminating the necessity for clutch mechanisms and/or mechanical variable speed drives typically used in existing rotary shears/cutters. Specifically, the motor accelerates and decelerates the oppositely totating cylinders and holds the velocity of the helical blades- equal to web velocity during the period of cut.

Another feature of the described rotary shear assembly is that the leading helical blade has a slightly greater rotational radius than does the following helical blade to prevent the following blade from scraping against the leading blade as they rotate out of engagement after shearing contact.

The unique mechanical features of the described rotary shear assembly i.e. the helical blade configuration, the hollow cylinders carrying the helical blades, the rigidity and stability provided to the oppositely rotating cylinders by the externally coupled cantilever support bearing frame and concrete filled structural frame, and the antibacklash gearing for driving the hollow cylinders combine to significantly reduce the mass and therefore inertia of the rotating components of the machine over that of existing rotary shear and cutter machines. It is this reduction of mass ergo enertia which enables the rotational period of the rotating cylinders to be regulated by controlling the direct motor drive. Also, the reduction in the rotational inertial mass makes rotary shearing operations possible at web velocities up to 1,000 feet per minute.

In addition, the unique and novel features of the described rotary shear assembly combine to minimize stresses on individual mechanical components, thus greatly increasing the operational lifetime of each component. Accordingly, the invented rotary shear will not require as extensive maintenance and repair as existing rotary shear and cutter machines.

Finally, other objects, advantages and novel features of the invented direct drive rotary shear machine will become apparent upon examination of the following detailed description of preferred embodiments of the machine together with the accompanying figures.

Figure 1 is a side elevation view of the rotary shear machine illustrating the relationship of a rigid frame structure, and counterbalancing cantiliver bearing frames with hollow cylinders carrying the helical blades.

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1.

Figure 3 is a partial cross-sectional view taken along line 3-3 of Figure 1 illustrating shearing engagement of the helical blades.

Figure 4 is a side elevation view taken along line 21 4 of Figure 3 showing the cutting blades helically secured to the cylinder's outer surface.

Figure 5 is a cross-sectional view of one of the hollow blades carrying cylinders and its supporting shafts.

Figure 6 is a diagrammatic perspective view of the rotary shear machine and a moving web of material.

Figure 7 is a top view of Figure 6 showing the angular realtionship between the rotational axes of the blade carrying cylinders and the direction of travel of the moving web of material.

Figure 8 is a block diagram of an exemplary control system designed to drive the rotary shear machine for successively cutting sheets of predetermined lengths from a moving web of material.

Figure 9 is a block diagram of an exemplary control system designed to drive the rotary shear machine for intermittently cutting a moving web of material.

Figure 10 is a diagrammatic end view of the hollow, blade carrying cylinders illustrating positioning of sensors and cams for intermittent operation.

Figure 11 is a diagrammatic end view of the hollow blades carrying cylinders angularly illustrating the region where the helical blades travel at the velocity of the moving web.

Figure 12 is a graph illustrating relationships between the velocity of web travel and the length of sheets cut from the web.

Figures 1 and 2 illustrate the structure and components of the invented rotary shear machine, including a concrete filled base frame member 22, a concrete filled lower cross-brace member 23, two bearing frame structures 24, and two upper concrete filled cross-brace members 26. Two parallel hollow cylinders 27 are supported within the frame defined by the bearing frames 24 and the upper and lower crossbrace members 23 and 26 by shafts 28 coaxially extending from the respective ends of the cylinders 27. Each extending shaft 28 is received by two bearings 29 and 31 mounted on an inside bearing plate 32 and an outside bearing plate 33 respectively of the bearing support frames 24. It should be noted that the shafts 28 extend completely through the bearing frames 24.

Antibacklash transmission gearing 34 couples the shafts 28 extending from the respective ends of the hollow cylinders 27 between the inside and outside bearings 29 and 31 within the bearing frame structure 24. For a detailed description of the antibacklash transmission gearing 34 coupling the parallel hollow cylinders 27, please refer to my teachings appearing in U.S. Patent No. 3,037,396. The antibacklash transmission gearing 34 coupling the oppositely extending shafts 28 balances opposing torsional forces experienced by the hollow cylinders 27 and the structural frame members supporting the cylinders respectively upon the acceleration and deceleration of rotation of the cylinders 27.

It should be noted that the antibacklash transmission gearing 34 also couples the shafts 28 such that the hollow cylinders 27 rotate in opposite directions.

A suitable driving gear 36 directly driven by a DC electrical motor 37 engages and drives the antibacklash transmission gearing 34 at one end of the rotary shear machine 21. The DC electrical motor 37 is mounted on a platform 38 suitably secured to outside bearing plate 33 of the bearing frame structure 24. As discussed in greater detail infra, the DC electrical motor 37 is utilized to accelerate and decelerate rotation 9f the hollow cylinders 27 to thus eliminate the necessity for brakes, cyclically variable mechanical transmission devices and/or clutch mechanisms for varying the rotational period of the cylinders 27.

Cutting blades 39 and 41 are secured helically across the cylindrical surface of the cylinders 27. The cutting blade 39 secured helically across the upper cylinder 27 is inclined at an angle o with respect to the longitudinal rotational axis of the upper cylinder 27 while the cutting blade 41 secured helically across the cylindrical surface of the lower cylinder 27 is inclined at an angle of (360Co) with respect to the longitudinal rotational axis of the lower cylinder 27, 8 being defined as the blade helix angle.

The cutting blades 39 and 41 are secured relative to each other on the respective surfaces of the cylinders 27 in such a rotational position that the blades progressively engage in shearing contact as the cylinders 27 rotate (see Figures 3 and 11). Web, material, such as paperboard, is received or threaded through the space 42 between the parallel cylinders 27.

Selection of the proper blade helix angle 0 is primarily dependent on the following factors: 1) The range of expected shear resistances of the materials to be cut; 2) The length of the cylinders carrying the blades (maximum web width); 3) The circumference of the cylinders carrying the blades; 4) The load carrying capabilities of the cylinders, shafts, bearings and bearing support frames; and 5) The operational capabilities of the power drive system rotating the cylinders.

For conventional corrugated paperboard webs having widths ranging up to 110 inches, blade helix angles ranging between 0.50 and 3 have been found suitable. The axial lengths of the blade helixes should be at least equal to the width of the moving web.

In the arrangement shown in Figures 1 and 2, the paperboard web would be moving into the drawing. Accordingly, upon rotation of the cylinders 27 the cutting blades 39 and 41 would progressively engage in shearing contact across their entire lengths, beginning at the left hand side of the machine 21 and completely sever or shear any web material moving in the space 42 between the cylinders 27.

The bearing frame structures 24 being complete enclosures also function as a container for bathing the antibacklash transmission gearing 34 in oil (not shown).

In fact, oil pumps 43 may be mounted in the base of the bearing frame structures 24 for spraying oil on the transmission gearing 34.

The oil pumps could be driven by a suitable chain drive unit 44 coupled to the shaft 28 of the lower cylinder 27.

Also, a shaft digital encoder 46 and rotational position cams 47 are directly coupled to the shaft 28 of the lower cylinder 27 as shown in phantom in Figure 1. Also shown in phantom in Figure 1 are cam sensors 48. The function of the digital encoder 46, the rotational position cams 47, and the cam sensors 48 will be discussed in greater detail infra.

Now, referring to Figures 3, 4 and 5, the cutting blades 39 and 41 are secured helically across the cylindrical surface of the cylinders 27 by blade holding assemblies 49.

The blade holding assemblies 49 each include a shoulder 51 defining a radial face 52 which spirals helically relative to the surface of the cylinder to which it is secured at a helix angle of 0, or(360"-8), depending upon whether the assembly 49 is secured to the upper or lower cylinder 27. The radial face 52 of the assembly 49 supports the back of the cutting blades, 39 and 41. Additional reinforcement for holding the cutting blades 39 and 41 at the precise helix angles is provided by reinforcing ribs 53 integral with the shoulder 51 at intervals along the length of the assembly 49. The assembly 49 further includes an integral platform 54 for supporting the base of the cutting blades 39 and 41. The blade holding assemblies 49 are secured to the surface of the cylinders 27 by appropriate bolt means 56.The cutting blades 39 and 41 are secured between the radial face 52 of the shoulders 51 and clamp bars 57 by a plurality of bolts 58.

A blade holding assembly 49 may be formed by a single integral piece helically winding around the cylindrical surface or by a plurality of units as shown in Figure 4. For balancing rotation of the cylinders 27, counter balances 50 are secured to the surface of the cylinders diametrically opposite from the blades 39 and 41 and holding assemblies 49.

Figure 3 illustrates the shearing engagement of the cutting blades 39 and 41 across their respective faces. The lower cutting blade 41 rotationally precedes the upper cutting blade 39. As shown in Figure 3, the faces of cutting blades 39 and 41 are vertically aligned. In order to prevent the cutting edge of the upper blade 39 from scraping against the face of the lower blade 41 as they are rotated out of engagement, the lower blade (which rotationally precedes the upper blade) is given a slightly greater radius of rotation than the upper blade 39. In the embodiment shown in Figure 3, cutting blade 41 is provided a slightly greater rotational radius than cutting blade 39 by placing a shim 63 between the base of the blade 41 and the platform 54 of the blade holding assembly 49.

Referring now to Figure 5, the shafts 28 each include an integral raised annular shoulder which is received in the interiors of the, hollow cylinders 27. The raised annular shoulders 64 are appropriately secured to the interior walls of the hollow cylinders 27 by welding and/or bolts.

Referring back to Figure 1, the bearing support frames 24 each include an inner bearing support plate 32 and an outer bearing support plate 33 and rigid side plates 66 holding the inner and outer bearing support plates 32 and 33 in rigid spaced relationship. The shafts 28 carrying the hollow cylinders 27 extend completely through the bearing support frames 24.

Accordingly, the bearing support frames provide counter balancing coupled cantilever support stiffening the shafts 28 and cylinders 27 against flexure as they rotate.

In particular, as the helical blades 39 and 41 carried by the hollow cylinders 27 shear the web materials, forces are generated which tend to bend or flex the cylinders 27 and shafts 28 apart. The flexure of the cylinders 27 and shafts 28 includes both vertical and horizontal components. Also, the flexure of the upper and lower cylinders and shafts 27 and 28 are oppositely directed.

If such flexure is permitted, good shearing engagement of the helical blades 39 and 41 cannot be maintained through the cut. To prevent such flexure, the outside bearing plates 33 and bearings 31 of the bearing frame structures 24 provide the external cantilever support to the respective cylinders and shafts 28, stiffening them against flexure in any plane. Specifically, the inner bearing plates 32 and inner bearings 29 provide fulcrums upon which the cylinders 27 and the portion of the shafts 28 inside of the bearings 29, on the one hand, and pme portion of the shafts 28 outside of the bearings 29, on hyj other hand, and the portion of the shafts 28 outside of the bearings 29, on the other hand, must pivot.The outside bearings 31 and the outside bearing plates 33 rigidly constrain or prevent movement of the shafts 28 extending beyond the inner bearings 29, hence, preventing movement of the shafts 28 and cylinders 27 inside the inner bearing 29. Since the inside and outside bearing plates 32 and 33 of the bearing frame structures 24 are common for both the upper and lower cylinder shafts 28 the forces tending to flex the cylinders and shafts apart are mechanically counter balanced. For example, any force tending to flex the lower cylinder 27 would induce a force acting on the ends of the shafts 28 extending beyond the inner bearings 29 which in turn induces a counter balancing force, tending to flex the upper cylinder in the same direction in the region between the inner bearings 29.

However, since any force tending to flex the lower cylinder would always have its equal and opposite force counterpart acting on the upper cylinder, - the respective forces transmitted by external (cantilever) bearings 31 simply cancel (counter balances) the forces tending to flex the upper and lower cylinders 27 apart. In fact, it is even possible to prestrain the cylinders and shafts 27 and 28 against anticipated bending flexure by mounting the inner and outer bearings 29 and 31, carrying same slightly out of coaxial alignment.

The concrete filled structural frame members, the base 22, the lower cross-brace 23, and the upper cross-brace members 26, coact with the bearing support frames 24 to enhance their rigidity. Specifically, as previously discussed, the bearing frame structures 24 each form a rigid structural box. The concrete support members resist forces tending to skew the bearing support frames 24 out of square. In addition, the bearing frame structures 24, being composed of structural metal, react elastically within a certain range, and cyclic stresses would establish elastic vibrations in the bearing frame structures 24. The concrete, having a very low elasticity modulus, would tend to damp elastic vibration in both the enclosing structural members and the bearing frame structures 24.

Referring now to Figures 6 and 7, to shear moving web of material 67 perpendicularly with respect to its direction of travel, the rotary shear machine must be inclined off square from the direction of web travel 59 at an angle equal to the blade helix angle 0. In particular, referring to Figure 7, the rotational axes of the cylinders 27 carrying the helical blades 39 and 41 are inclined at angle 0 off square with the direction of travel 59 of the web material 67. When so inclined, the rotary shear machine 21 cut sheets 68 perpendicularly from the web 67.

Sandwich rollers 69 or other conventional means may be used to maintain the angular relationship between the travelling web 67 and the rotational axis of the cylinders 27.

Perpendicular cuts across the web are indicated at 71.

For perpendicular cuts the minimum axial length "L" of the blade helix is given by the formula: L=W cosec 0 where 0 is the blade helix angle and "W" is maximum width of web can be severed by a particular rotary shear machine.

Referring now to Figure 8 through 12, the invented rotary shear machine when inclined at the helix angle 0 off square with the direction of travel 59 of the web 67 may be operated and controlled for successively cutting sheets 68 of predetermined lengths from the moving web 67. Specifically, as diagrammatically shown in Figure 8, the velocity of the moving web of material 67 may be sensed by a digital encoder which generates digital pulses bearing a predetermined relationship to the velocity of the moving web. The rotational velocity of a shaft carrying one of the hollow cylinders 27 is also sensed by a digital ericoder 46.The digital signals from the web velocity digital encoder and the shaft velocity digital encoder are input into a Digital Cut-To-Length Control of a type manufactured by Dynapar Corporation, headquartered in Gurnee, Illinois. The desired sheet length is manually selected and input into- the Digital Cut-To-Length Control with the manual Preset Cut-To Length Control. The Digital Cut-To-Length Control compares signals received from the web velocity digital encoder and the shaft velocity digital encoder to the information received from the manual Preset Cut-To Length Control and accordingly regulates a regenerative DC Motor Control which in turn controls the DC motor 37 directly driving the rotating cylinder 27 via the driving gear 36. Suitable regenerative DC motor controls are manufactured by Randtronics, Menlo Park, California, e.g.

their model TB 750, Regenerative DC Motor Control. Finally, an end cut sensor inputs a signal into the Digital Cut-To Length Control, telling the control when the machine has completed a cut.

More particularly, referring to Figure 11 the period of cut p of the helical blades 39 and 41 is angularly illustrated. In particular, angle y designates the degrees of arc which the cylinders 27 must rotate for complete engagement of the helical blades 39 and 41 across their entire lengths. Angle p designates the degrees of arc through which arbitrarily small segments of the blades 39 and 41 overlap. Angles A designate safety margin degrees of arc through which it is desirable to drive the blades at web velocity prior to the point 72 of initial blade engagement and subsequent to the point 73 where the blades no longer overlap. Blades 39 and 41 are shown at point 73 in the figure.

The lines 74 show the locus of the cutting edges of the blades 39 and 41 as the cylinders 27 rotate.

Since the web material 67 has a thickness 't', the helical blades 39 and 41 will initially contact the web material prior to the point 72 of initial blade contact. Accordingly, it may be desirable to include in the manual Preset Cut-To-Length Control an adjustment for the thickness of material to be cut for adjusting the safety margin angles A relative to thickness of the material to be cut. The sum of the angles, 2A+p+v-p where ss is the angular equivalent of the period of cut. In other words, the helical blades should be rotated at the velocity of the moving web throughout angle P.

The shaft digital encoder 46 produces signals both indicative of the rotational position and velocity of the helical blades carried by the hollow cylinders 27 as shown in Figure 8.

Referring now to Figures 1 and 10, two rotational position cams 47 are secured to a shaft 28 carrying one of the helical blades.

The rotational position cams 47 are a rest position cam 76 and an end cut position cam 77. The cams generate signals in two cam sensors, 48a and 48b, which are mounted in a common plane 75 parallel to the longitudinal axis of the shaft 28 to which the rotational position cams are mounted.

The cam sensors 48a and 48b may be variable reluctance transducers for generating electrical signals responsive to changes of magnetic field reluctance, the rotational position cams 47 being composed of magnetically susceptible materials. Accordingly, as the rotational cams 47 rotate, the sensors 48a and 48b will generate electrical signals corresponding to the rotational positions of the cams 47. Alternatively the rotational position cams 47 could be a conventional rotating cam surface and the sensor 48 conventional cam followers.

The end position cam 77 is positioned on the shaft 28 such that it passes through the plane 75 of the cam sensors 48 at the end of the period of cut p, thus generating a signal that tells the Digital Cut-To-Length Control that the cut is complete and the rotation of the helical blades may be accelerated and/or decelerated, depending upon the length of sheet to be cut.

In more detail, referring to the graph Figure 12 showing relationships between the sheet length to be cut in inches and the velocity of the web in feet per minute (f.p.m.), the curve 78 designates the shortest sheet which may be cut without driving the DC motor beyond its normal operational range. The line 79 designates the length of sheet which would be cut when the helical blades rotate synchronously at web velocity.

the curve 81 shows the maximum web velocity above which sheets cannot be cut without driving the DC motor beyond its normal operational range.

(Note: the data and information pre sented in the graph of Figure 12 is pre sented solely for the purposes of illustration and the actual curves 78, 79 and 81 will vary depending upon inertia of the rotating components, the radius of the cylinders and blades, and the capabilities of the particular DC electrical motor drives, as well as other factors).

The area bounded by the curves 78 and 81 designates the operational range of an exemplary rotary shear machine 21. In particular, if the blades are rotating synchronously with web velocity, the length of sheet will approximately equal the circumference of a cylinder having the same radius as the radial distance from the axis of rotation to the cutting edges of the helical blades 39 and 41.If the sheets to be cut are shorter than synchronous length 79, then upon receiving the end of cut signal, the Digital Cut-To-Length Control will accelerate the helical blades to a velocity greater than web velocity, and then at some point before the period of cut A, decelerate the helical blades such that they reach web velocity at the beginning of the period of cut /3. If the length of sheets to be cut is longer than the synchronous length, then upon receiving the end of cut signal, the Digital Cut-To-Length Control will decelerate rotation of the helical blades below web velocity and then at some point before the period of cut, accelerate the helical blades such that they reach web velocity at the beginning of period of cut A. In fact, the Digital Cut-To-Length Control should be designed such that it minimizes electrical power consumption by the DC motor drive as it accelerates and decelerates (brakes) rotation of the helical blades.

Referring now to Figures 9 and 10, an exemplary intermittent shear control system for the invented rotary shear machine is described. The control system (Figure 9) includes a web velocity sensotachometer generator which generates a voltage bearing a predetermined relationship to web velocity, and a motor sensor tachometer generator driven by the DC motor 37 which generates a voltage bearing a predetermined relationship to the rotational velocity of the blades 39 and 41. The control system also includes a Regenerative DC Motor Control 80 which controls power delivery to the DC motor. Such controls 80 typically include drive logic circuitry and drive power switching circuitry. The drive logic circuitry compares the voltage signals received from the tachometer generators, sensing web and blade velocity.Also, signals from the manual switch, the rest position sensor and the end cut sensor are input into the drive logic circuitry section of the regenerative DC Motor Control 80.

For intermittent shearing operations, the helical blades do not continuously rotate as in the case of sheet production, but rather come to a halt at a rest position. Figure 10 angularly illustrates an examplary rest position for the helical blades 39 and 41, the arrows 59, 61 and 62 indicating the direction of web travel and cylinder rotation, respectively. As shown in Figure 10, the leading edge of the rest position cam 76 lies in the sensor plane 75.To initiate a shear, the manual switch is manually tripped whereupon the regenerative DC Motor Control 80 supplies power to the DC motor 37 to accelerate rotation of the helical blades 39 and 41 until the voltage signal generated by the motor sensor tachometer matches that of the web velocity sensor tachometer at which point the Control 80 simply supplies sufficient power to the motor to maintain matching voltage signals from the respective sensors. At the point of the motor sensor tachometer generates a voltage equal to that generated by the web sensor tachometer the helical blades 39 and 41 are rotating at web velocity.Thus, the regenerative DC Motor Control, by supplying sufficient power to the DC motor 37 to maintain matching voltage signals of the web and motor sensor tachometer, the velocity of the rotating blades are held at web velocity until a signal is received from the end cut sensor. Upon the end cut cam 77 passing through the sensor plane 75, the end cut sensor 48b generates a signal which causes the regenerative DC Motor Control 80 to decelerate the DC motor 37 to creep velocity. The motor continues to drive at creep velocity until the rest position cam 76 passes through the sensor plane 75 to generate a signal from the rest position sensor 48a.Upon receiving a signal from the rest position sensor, the regenerative sensor DC Motor Control 80 causes the DC motor 37 to drive back and forth until the leading edge of the rest position cam 76 lies in the sensor plane 75.

At the rest position shown in Figure 10, the blades 39 and 41 will rotate through 1800 before the period of cut p. However, as is apparent from the figure, the helical blades 39 and 41 do not rotate 1800 from the end of period of cut /3 to the rest position. While the motor 37 can rapidly decelerate the rotation of the helical blades, at high web velocities it will be unable to decelerate the helical blades to creep velocity before the leading edge of the rest position cam 76 passes through the sensor plane 75.

Accordingly, the rest position cam 76 will continue to generate a signal throughout a 90" rotation period which under normal circumstances would provide sufficient room for deceleration to creep velocity without exceeding the normal operational capabilities of the DC motor 37. If the leading edge of the rest position cam 76 passes through the sensor plane 75, then upon reaching creep velocity the regenerative DC Motor Control will reverse the DC motor and rotate the helical blades backwards until the leading edge of the rest position cam 76 lies in the sensor plane.

The described control systems for the invented rotary shear machine are of an exemplary nature. There can be many modifications of the particular control sequences for varying the rotational periods of the helical blades carried by the hollow cylinders. The principal factors which must be considered in designing such control systems are as follows: 1) The period of cut P, i.e. the time and/or angular interval in which the helical blades must move at web velocity; 2) The mass and inertia of the rotating components of the machine; 3) The operational capabilities of the DC electrical motor driving the rotating components of the shear; 4) The range of expected shear resistance of the materials to be cut; and 5) The expected velocity range of the moving web.

WHAT I CLAIM IS: 1. A rotary shear machine for transversely severing a moving web of material of any width, comprising a pair of spaced parallel cylinders, means for oppositely rotating said cylinders and for regulating the rotational cycle of said oppositely rotating cylinders, said web of material moving between said oppositely rotating cylinders, a blade secured longitudinally along the surface of each cylinder in a helix, said helix having an axial length at least equal to the width of said web of moving material, one blade bearing a helical angular relationship of 0 to the longitudinal axis of the cylinder to which it is secured, the other blade bearing a helical angular relationship of (36000) to the longitudinal axis of the cylinder to which it is secured, 8 being a blade helix angle, said blades positioned relative to each other on the respective cylinders to mesh progressively in shearing engagement along their entire lengths as said cylinders oppositely rotate for shearing any material moving between said spaced parallel cylinders.

2. A rotary shear machine according to Claim 1 wherein one helical blade rotationally precedes the other helical blade carried by the oppositely rotating cylinder and has a slightly greater rotational radius measured from the longitudinal axis of the cylinder to which it is secured than the other helical blade whereby arbitrarily small sections along the lengths of said respective blades only touch in shearing engagement.

3. A rotary shear machine according to Claim 1 wherein the axis of rotation of said oppositely rotating cylinders are positioned at an angle of 90" plus the blade helix angle 0 relative to the direction of travel of said moving web of material, and wherein said helixes of said blades have a minimum axial length ("L") given by the relationship: L=W cosec 0, where "L" is the axial length of the blade helix, "W" is a maximum width of web materials which may be severed, and 0 is the blade helix angle whereby said web of material is transversely severed perpendicular to its direction of travel.

4. A rotary shear machine according to Claim 1 wherein said spaced parallel cylinders are hollow.

5. A rotary shear machine according to Claim 3 wherein the rotational cycle of the oppositely rotating cylinders includes a period of cut beginning at a point where said helical blade rotates into initial engagement with the web material and ending at a point where said helical blades rotate out of engagement with said web material, and wherein said means for oppositely rotating and for regulating the rotational cycle of said oppositely rotating cylinders includes means for maintaining velocity of the helical blades secured to the surface of the oppositely rotating cylinders at that of the moving web during said period of cut.

6. A rotary shear machine according to Claim 4 further including the improvement comprising rigid box frame structures supporting said oppositely rotating cylinders at their respective ends for minimizing bending flexure of said cylinders as they rotate, each rigid box frame structure including inner and outer bearing support plates held in spaced relation by rigid side plates, a pair of inner bearings fixed in each inner bearing support plate each inner bearing in axial alignment with a shaft extending coaxially from one end of each of said pair of spaced parallel cylinders, said shafts extending through said inner bearings; a pair of outer bearings fixed in each outer bearing plate each outer bearing in axial alignment with one of said shafts extending from the ends of said cylinders through said inner bearings, said shafts extending through said outer bearings, said outer bearings and outer bearing plates of said box frame structures providing coupled counter balancing cantilever support stiffening said cylinders against forces tending to flex said cylinders apart as they oppositely rotate.

7. A rotary shear machine according to Claim 6 further including a brace means secured between said rigid box frame structures for holding said box frame structure in rigid parallel spaced relationship.

8. A rotary shear machine according to Claim 7 wherein said brace means include a base structure and at least one structural cross-brace member.

9. A rotary shear machine according to Claim 7 wherein said base structure and cross-brace members are tubular and are filled with concrete.

10. A rotary shear machine according to Claim 6 further including the improvement comprising backlash preventing gear transmission means coupling the shaft pairs extending from the opposite ends of said cylinders in a region between said inner and outer bearings within said box frame structures for minimizing torsional flexure of said cylinders upon acceleration and deceleration of rotation thereof.

1I. A rotary shear machine according to

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Claims

**WARNING** start of CLMS field may overlap end of DESC **.

2) The mass and inertia of the rotating components of the machine;

3) The operational capabilities of the DC electrical motor driving the rotating components of the shear;

4) The range of expected shear resistance of the materials to be cut; and

5) The expected velocity range of the moving web.

WHAT I CLAIM IS: 1. A rotary shear machine for transversely severing a moving web of material of any width, comprising a pair of spaced parallel cylinders, means for oppositely rotating said cylinders and for regulating the rotational cycle of said oppositely rotating cylinders, said web of material moving between said oppositely rotating cylinders, a blade secured longitudinally along the surface of each cylinder in a helix, said helix having an axial length at least equal to the width of said web of moving material, one blade bearing a helical angular relationship of 0 to the longitudinal axis of the cylinder to which it is secured, the other blade bearing a helical angular relationship of (36000) to the longitudinal axis of the cylinder to which it is secured, 8 being a blade helix angle, said blades positioned relative to each other on the respective cylinders to mesh progressively in shearing engagement along their entire lengths as said cylinders oppositely rotate for shearing any material moving between said spaced parallel cylinders.
2. A rotary shear machine according to Claim 1 wherein one helical blade rotationally precedes the other helical blade carried by the oppositely rotating cylinder and has a slightly greater rotational radius measured from the longitudinal axis of the cylinder to which it is secured than the other helical blade whereby arbitrarily small sections along the lengths of said respective blades only touch in shearing engagement.
3. A rotary shear machine according to Claim 1 wherein the axis of rotation of said oppositely rotating cylinders are positioned at an angle of 90" plus the blade helix angle 0 relative to the direction of travel of said moving web of material, and wherein said helixes of said blades have a minimum axial length ("L") given by the relationship: L=W cosec 0, where "L" is the axial length of the blade helix, "W" is a maximum width of web materials which may be severed, and 0 is the blade helix angle whereby said web of material is transversely severed perpendicular to its direction of travel.
4. A rotary shear machine according to Claim 1 wherein said spaced parallel cylinders are hollow.
5. A rotary shear machine according to Claim 3 wherein the rotational cycle of the oppositely rotating cylinders includes a period of cut beginning at a point where said helical blade rotates into initial engagement with the web material and ending at a point where said helical blades rotate out of engagement with said web material, and wherein said means for oppositely rotating and for regulating the rotational cycle of said oppositely rotating cylinders includes means for maintaining velocity of the helical blades secured to the surface of the oppositely rotating cylinders at that of the moving web during said period of cut.
6. A rotary shear machine according to Claim 4 further including the improvement comprising rigid box frame structures supporting said oppositely rotating cylinders at their respective ends for minimizing bending flexure of said cylinders as they rotate, each rigid box frame structure including inner and outer bearing support plates held in spaced relation by rigid side plates, a pair of inner bearings fixed in each inner bearing support plate each inner bearing in axial alignment with a shaft extending coaxially from one end of each of said pair of spaced parallel cylinders, said shafts extending through said inner bearings; a pair of outer bearings fixed in each outer bearing plate each outer bearing in axial alignment with one of said shafts extending from the ends of said cylinders through said inner bearings, said shafts extending through said outer bearings, said outer bearings and outer bearing plates of said box frame structures providing coupled counter balancing cantilever support stiffening said cylinders against forces tending to flex said cylinders apart as they oppositely rotate.
7. A rotary shear machine according to Claim 6 further including a brace means secured between said rigid box frame structures for holding said box frame structure in rigid parallel spaced relationship.
8. A rotary shear machine according to Claim 7 wherein said brace means include a base structure and at least one structural cross-brace member.
9. A rotary shear machine according to Claim 7 wherein said base structure and cross-brace members are tubular and are filled with concrete.
10. A rotary shear machine according to Claim 6 further including the improvement comprising backlash preventing gear transmission means coupling the shaft pairs extending from the opposite ends of said cylinders in a region between said inner and outer bearings within said box frame structures for minimizing torsional flexure of said cylinders upon acceleration and deceleration of rotation thereof.
1I. A rotary shear machine according to

Claim 5 wherein said means for oppositely rotating said cylinders and for regulating the rotational cycle of said oppositely rotating cylinders comprise in combination, a reversible DC electrical motor having a drive shaft, means for directly coupling the drive shaft of said DC electrical motor to said spaced parallel cylinders for oppositely rotating said cylinders, DC Motor Control means for supplying electrical power to said DC electrical motor, a web sensor means for generating electrical signals bearing a predetermined relationship to velocity of said moving web of material, a shaft sensor means for generating electrical signals bearing a predetermined relationship to both angular position and velocity of said blades helically secured to said oppositely rotating cylinders, end cut sensor means for generating an electrical signal indicating said helical blades have rotated through said period of cut, selecting means for manually selecting a length sheet desired to be cut from said moving web of material, said selective means establishing electrical relationships bearing a predetermined relation to said desired sheet length manually selected, a logic control means for regulating said DC Motor Control means responsive to electrical signals received from said web sensor means, said shaft sensor means and said end cut sensor means in accordance with the electrical relations established by said selecting means, said DC Motor Control means supplying electrical power to said DC motor responsive to said logic control means, said DC electrical motor accelerating and decelerating rotation of said oppositely rotating cylinders 1) for moving the helical blades at the velocity of the moving web of material during the period of cut, and 2) for varying the rotational cycle of said oppositely rotating cylinders whereby sheets of the desired lengths may be transversely severed from the moving web of material perpendicular to its direction of travel.
12. A rotary shear machine according to Claim 5 wherein said means for oppositely rotating and for regulating the rotational cycle of said oppositely rotating cylinders comprises in combination, a reversible DC electrical motor having a drive shaft, means directly coupling the drive shaft of said DC motor to said cylinders for oppositely rotating said cylinders, web sensor means for generating an electrical voltage signal bearing a predetermined relationship to the velocity at which the web material moves, end cut sensor means for generating an electrical signal indicating said helical blades have rotated through said period of cut, a motor sensor means for generating an electrical voltage signal bearing a predetermined relationship to the velocity at which the helical blades rotate, a rest position sensor means for generating an electrical signal indicating said helical blades are angularly positioned at a rotational rest position outside the period of cut, regenerative DC Motor Control means for regulating electrical power supplied to said DC electrical motor responsive to electrical signals received from said web sensor means, said end cut sensor means, said rest position sensor means and said motor sensor means, a switching means connected to said regenerative DC Motor Control means for manually initiating a single rotational cycle of said oppositely rotating cylinders, said rotational cycle beginning with the helical blades at the rotational rest position, said regenerative DC Motor Control means regulating electrical power supplied to said DC electrical motor 1) for accelerating rotation of said helical blades to the velocity of said moving web,

2) then for maintaining the velocity of said rotating helical blades at the velocity of said moving web until said helical blades rotate through said period of cut responsive to the electrical voltage signals from the web sensor means and motor sensor means, 3) then for decelerating rotation of said helical blades to a creep velocity responsive to the electrical signal from said end of cut sensor means and finally 4) for halting rotation of said helical blades responsive to electrical signals from said rest position sensor means, said helical blades being angularly positioned at the rotational rest position.
13. A rotary shear machine according to Claim 3 wherein the blade helix angle o ranges from 0.50 to 30.
14. A rotary shear machine for transversely severing a moving web of material of any width comprising in combination, a rigid frame structure, a pair of spaced parallel cylinders within said frame structure, said web material moving between said pair of spaced parallel cylinders, bearing means for rotatably supporting said pair of spaced parallel cylinders and for providing counter balancing cantilever support to minimize bending flexure of said cylinders, backlash preventing gear transmission means coupling the opposite ends of said spaced parallel cylinders for minimizing torsional flexure of said cylinders and torsional flexure of said frame structure upon rotation of said cylinders, and for causing said cylinders to rotate in opposite directions, driving means for rotating said pair of spaced parallel cylinders, means for directly coupling said driving means to said pair of spaced parallel cylinders, said cylinders rotating oppositely about their respective longitudinal axes, a blade secured longitudinally along the surface of each cylinder in a helix, said helix having an axial length at least equal to the width of said web of moving material, one blade bearing an angular relationship of 0 to the longitudinal axis of the cylinder to which it is secured, the other blade bearing an angular relationship of (3600o) to the longitudinal axis of the cylinder to which it is secured, 0 being a blade helix angle, said blades positioned relative to each other on the respective cylinders to mesh progressively in shearing engagement along their entire lengths as said cylinders oppositely rotate for shearing any material between said spaced parallel cylinders, control means regulating said driving means for accelerating and decelerating rotation of said cylinders whereby a rotational cycle of said blades helically secured to said oppositely rotating cylinders may be varied, every rotational cycle of the rotating helical blades including a period of cut beginning at a point where said helical blades are rotated into initial engagement with the web material moving between said spaced parallel cylinders and ending at a point where said helical blades are rotated out of engagement with said web material, said means regulating said driving means such that said helical blades rotate at a velocity equal that of said moving web of material during said period of cut.
15. A rotary shear machine according to Claim 14 wherein one helical blade rotationally precedes the other helical blade carried by the oppositely rotating cylinder and has a slightly greater rotational radius measured from the longitudinal axis of the cylinder to which it is secured than the other helical blade whereby arbitrarily small sections along the lengths of said respective blades only touch in shearing engagement.
16. A rotary shear machine according to Claim 14 wherein the axis of rotation of said oppositely rotating cylinders are positioned at an angle of 90" plus the blade helix angle 0 relative to the direction of travel of said moving web of material, and wherein said helixes of said blades have a minimum axial length ("L") given by the relationship: L=W cosec 0, where "L" is the axial length of the blade helix, "W" is a maximum width of web materials which may be severed, and 0 is the blade helix angle whereby said web of material is transversely severed perpendicular to its direction of travel.
17. A rotary shear machine according to Claim 13 wherein said spaced parallel cylinders are hollow.
18. A rotary shear machine according to Claim 17 wherein said bearing means for providing counter balancing cantilever support to minimize bending flexure of said cylinders comprises in combination, rigid box frame structures forming sides of said frame structure supporting said cylinders at their respective ends each rigid box frame structure including inner and outer bearing support plates held in spaced relation by rigid side plates, a pair of inner bearings fixed in each inner bearing support plate each inner bearing in axial alignment with a shaft extending coaxially from one end of each of said pair of space parallel cylinders, said shafts extending through said inner bearings, a pair of outer bearings fixed in each outer bearing plate each outer bearing in axial alignment with one of said shafts extending from the ends of said cylinders through said inner bearings, said shafts extending through said outer bearings, said outer bearings and outer bearing plates of said box frame structures providing coupled counter balancing cantilever support stiffening said cylinders against forces tending to flex said cylinders apart as they oppositely rotate.
19. A rotary shear machine according to Claim 18 further including a brace means secured between said rigid box frame structures for holding said box frame structure in rigid parallel spaced relationship.
20. A rotary shear machine according to Claim 19 wherein said brace means include a base structure and at least one structural cross-brace member.
21. A rotary shear machine according to Claim 20 wherein said base structure and cross-brace members are tubular and are filled with concrete.
22. A rotary shear machine according to Claim 18 wherein backlash preventing gear transmission means couple the shaft pairs extending from the opposite ends of said cylinders in a region between said inner and outer bearings within said box frame structure.
23. A rotary shear machine according to Claim 16 wherein said driving means comprises a reversible DC electrical motor having a drive shaft, and wherein said control means comprises in combination, DC Motor Control means for supplying electrical power to said DC electrical motor, a web sensor means for generating electrical signals bearing a predetermined relationship to velocity of said moving web of material, a shaft sensor means for generating electrical signals bearing a predetermined relationship to both angular position and velocity of said blades helically secured to said oppositely rotating cylinders, end cut sensor means for generating an electrical signal indicating said helical blades have rotated through said period of cut, selecting means for manually selecting a length sheet desired to be cut from said moving web of material, said selective means establishing electrical relationships bearing a predetermined relation to said desired sheet length manually selected, a logic control means for regulating said DC Motor Control means responsive to electrical signals received from said web sensor means, said shaft sensor means and said end cut sensor means in accordance with the electrical relations established by said selecting means, said DC Motor Control supplying electrical power to said DC motor responsive to said logic control means, said DC electrical motor accelerating and decelerating rotation of said oppositely rotating cylinders 1) for moving the helical blades at the velocity of the moving web of material during the period of cut, and 2) for varying the rotational cycle of said oppositely rotating cylinders whereby sheets of the desired lengths may be transversely severed from the moving web of material perpendicular to its direction of travel.
24. A rotary shear machine according to Claim 16 wherein said driving means comprises a reversible DC electrical motor having a driving shaft and wherein said control means comprises in combination, web sensor means for generating an electrical voltage signal bearing a predetermined relationship to the velocity at which the web material moves, end cut sensor means for generating an electrical signal indicating said helical blades have rotated through said period of cut, a motor sensor means for generating an electrical voltage signal bearing a predetermined relationship to the velocity at which the helical blades rotate, a rest position sensor means for generating an electrical signal indicating said helical blades are angularly positioned at a rotational rest position outside the period of cut, regenerative DC Motor Control means for regulating electrical power supplied to said DC electrical motor responsive to electrical signals received from said web sensor means, said end cut sensor means, said rest position sensor means and said motor sensor means, a switching means connected to said regenerative DC Motor Control means for manually initiating a single rotational cycle of said oppositely rotating cylinders, said rotational cycle of said oppositely rotating cylinders, said rotational cycle beginning with the helical blades at the rotational rest position, said regenerative DC Motor Control means regulating electrical power supplied to said DC electrical motor 1) for accelerating rotation of said helical blades to the velocity of said moving web,

2) then for maintaining the velocity of said rotating helical blades at the velocity of said moving web until said helical blades rotate through said period of cut responsive to the electrical voltage signals from the web sensor means and motor sensor means, 3) then for decelerating rotation of said helical blades to a creep velocity responsive to the electrical signal from said end of cut sensor means and finally 4) for halting rotation of said helical blades responsive to electrical signals from said rest position sensor means, said helical blades being angularly positioned at the rotational rest position
25. A rotary shear machine according to Claim 16 wherein the blade helix angle 0 ranges from 0.50 to 30.
26. A rotary shear machine according to Claim 23 wherein said end cut sensor means comprises in combination a variable reluctance transducer for generating an electrical signal responsive to a change of magnetic field reluctance having a sensing face mounted perpendicularly with respect to one of said cylinder shafts, and a cam composed of magnetically susceptible material secured to said shaft angularly positioned relative to said transducer such that it is radially aligned with and proximate to the sensor face of said transducer at the end of the period of cut.
27. A rotary shear machine according to Claim 24 wherein said end cut sensor means comprises in combination a first variable reluctance transducer for generating an electrical signal responsive to a change of magnetic field reluctance having a sensing face mounted perpendicularly with respect to one end of said cylinder shafts, and a first cam composed of magnetically susceptible materials secured to said shaft angularly positioned relative to said first transducer such that it is radially aligned with and proximate the sensing face of said transducer at the end of said period of cut, and wherein said rest position sensor means comprises in combination, a second variable reluctance transducer for generating an electrical signal responsive to a change of magnetic field reluctance having a sensing face mounted perpendicularly with respect to said cylinder shaft, and a second cam composed of magnetically susceptible material secured to said shaft angularly positioned relative to the second transducer such that.it is radially aligned with and proximate the sensing face of said second transducer when said helical blades are at the rotational rest position.
28. A rotary shear machine according to Claim 27 wherein the second cam has a cam face subtending 90" of arc, and is angularly positioned on said shaft such that its leading edge is radially aligned proximate the sensing face of the second transducer when said helical blades are at the rotational rest position, and wherein said regenerative DC Motor Control means responsive to electrical signals from said second transducer, supplies electrical power to said reversible DC electrical motor for rotating and reversibly rotating said cylinders at creep velocity until the leading edge of said second cam is aligned radially with and proximate to the sensing face of the second cam. ~~~~~~~~~~~~~~~~~~~~~