US2764217A

US2764217A - Machine for making box blanks

Info

Publication number: US2764217A
Application number: US338030A
Authority: US
Inventors: Walter J Goettsch
Original assignee: Samuel M Langston Co
Current assignee: Samuel M Langston Co
Priority date: 1953-02-20
Filing date: 1953-02-20
Publication date: 1956-09-25
Anticipated expiration: 1973-09-25

Description

Se t. 25, 1956 w. J. GOETTSCH MACHINE FOR MAKING BOX BLANKS 2 Sheets-Sheet 1 Filed Feb. 20, 1953 Sept. 25, 1956 w. J. GOETTSCH MACHINE FOR MAKING BOX BLANKS 2 Sheets-Sheet 2 Filed Feb. 20, 1953 2 W 4 f- 5 ATTORNEY 4 mm M N m R m %N. fi, 1%2 |Umwzw WEE- 4 4 mm F 1 1% Q QM M m n \Q a J R A @N \T l b w 36% m mud mm k W\ ww @9529. $-mor05 0* w Nacho: 0% NW. m. \N V m R mm L w G um mo 6 W mmwm SN QN QN QR \N n L: @QEI Q I F QQEI .|.r QM Q, 6N RQ QQL United States Patent MACHINE FOR MAKING BOX BLANKS Walter J. Goettsch, Kenilworth, Ill., assignor to Samuel M. Langston Co., Camden, N. J., a corporation of New Jersey Application February 20, 1953, Serial No. 338,030

2 Claims. (Cl. 154-1) This invention is an improvement in machines of the type shown and claimed in my Patent 2,309,728, granted Feb. 2, 1943, and used for producing and continuously advancing a web of stiff sheet material, slitting and scoring it, and then cutting it transversely into successive sections constituting box blanks.

In the machine of that patent and in the present invention there are provided a series of operating units which act in succession on the stiff sheet as it is continuously produced and advanced. These include a cutter at the delivery end of the double facer, and whichis operated to sever the web just before the slowing down of the double facer and the adjusting of the other units for making box blanks of a different size or shape.

Beyond this cutter there is provided a slitter andscorer of the general type shown in the Behrens Patent 2,291,-

789,, and having a plurality of sets of slitting and scoring blades mounted on different radial arms of a rotatable frame, and provided with gears for transmitting power to those blades which are in operating position. A motor is provided for rotating the frame to swing one set of blades out of operative position after a given number of blanks of one size or shape have been cut, and swinging another set into position preparatory to starting the making of blanks of a different size and/ or shape, and a separate motor is provided for rotating the blades of a slitter-scorer.

Beyond the slitter-scorer is a unit which has separate portions for transversely cutting into sections the strips separated by the slitting blades, and thus form the box blanks. This cut-off may be of the type shown in the Behrens Patent 2,262,913, and has a motor to adjust the timing of its operations so as to cut off longer or shorter sheets. A main motor is provided for driving the double facer, the cut-off at the delivery end thereof, and the blades of the units which cut the scored strips into separate box blanks; and a plurality of small motors are provided for adjusting these units.

A plurality of connected motor-driven cams are employed to close and open the switches of the various solenoids in the proper sequence, and these open and close the switches of the various timing motors. These cams may be relatively adjusted to provide the proper sequence of operations.

When it is desired to bring into position a different set of preadjusted slitting and scoring blades and/ or to adjust the. units which cut the slitted and scored strips into sections, the web is severed, and the differential is operated to slow down the double facer, but without slowing down the severed sections of the web. Thus a gap is formed, and when thegap is at the slitter-scorer a motor on the latter is operated to bring a different set of blades into operating position. When the gap is at the unit which cuts the scored strips into sections a motor is operated to adjust this unit.

The main objects of the present invention are to simplify and reduce the cost of the mechanism required for effecting all of the adjustments necessary for the making of blanks of a different shape and/or size; to permit the use of a simpler and cheaper slitter-scorer; to secure increased accuracy in the making of the adjustments while the machine is running at reduced speed, and to reduce the time required for making the adjustments. This time saving is particularly important where the machine must be frequently adjusted to make small batches of blanks of different sizes or relative proportions, and it is also important that the time the sheet remains in the double facer during the making of the adjustments be reduced to the minimum, as overheating tends to make the blanks brittle.

As one feature of the present invention the cut-ofi at the delivery end of the double facer is provided with a motor for operating it when it is desired to adjust the units which act on the web.

As a further feature of the invention the differential is of the motor driven type, and is positioned in the main drive between the slitter-scorer and the unit which cuts the slitted and scored strips into sections. This may be operated to slow down the double facer after the web has been cut in two at the delivery end thereof, but the cut off section continues to travel at a higher speed than that of the web so as to form a gap and permit a different set of slitting and scoring blades to be brought into operative position.

As a further feature the slitting and scoring blades are normally driven from the main motor, but a separate motor is provided for keeping the rotational speed of these blades the same as the linear speed of the severed section of the web after the web has been transversely severed and the double facer has been slowed down, and until the rear end of the severed section has passed the slider-scorer.

While the machine is operating to make blanks for boxes of a particular shape and size the preselector on the slitter-scorer and the cut-off are set for the adjustments required for the next order of blanks for boxes of different proportions. After bringing the machine to a predetermined speed a motor is energized to give the cam shaft one revolution. During this revolution the cams control the stopping and starting of the reversible adjusting motors, and then the machine is brought up to normal operating speed.

A machine embodying the invention is shown somewhat diagrammatically in theaccompanying drawing, in which:

Fig. l is a schematic plan view of the machine.

Fig. 2 is a side elevation.

Fig. 3 is a section on the line 3-3 of Fig. 1.

Figs. 4a, 4b and 4c show the knife blades in three positions through which they pass, and the associated control switch; and

Fig. 5 is a wiring diagram of the controls for the motors and other units.

The various units acting on the sheet may be of the same general character as those shown in my patent above referred to, except as hereinafter noted. In these 'units, as shown in Figs. 1 and 2, the stiff sheet of double faced corrugated board is produced in the double facer 1t), and between belts on pulleys 11 and 12, and is delivered through a shear 13 which, as previously noted, is operated only at the completion of one order and preparatory to making adjustments for the next order. The board then passes through the slitter-scorer 14 and then to the cut-oil 15, which is driven from the line shaft 42, and the finished box blanks are discharged onto a conveyor 17. In some cases there may be two cut-offs, each acting on a different one of the strips which have been separated at the slitter-scorer 14, and two conveyors, one from each cut-off.

As in my patent above identified, various of the sec- 3 tions may be adjusted by motors to form different sizes and types of blanks. The cut-off 13 has a pair of rotary knives 19 and 20 which may be rotated through a single revolution by a motor 21.

The slitter-scorer is preferably of the type shown in Behrens Patent 2,291,789, and in Figs. 11 and 12. of my Patent 2,309,728, and in which there are three sets of cutting and scoring blades, each set being on a different pair of shafts mounted on a separate pair of radial arms. Thus, while the blades on one pair of arms are operating on a web, those on another pair of arms may be adjusted to the extent required for the next order of box blanks. Beyond the slitter-scorer 14 the web passes to the cutoff mechanism. The cut-off unit 15 may be of the type shown in Fig. 16 of my Patent 2,309,728, and may be adjusted by a motor 24 to cut the web into sections of the desired length, and equal to the periphery of the desired box.

The double facer is driven by a large D. C. motor 30, the speed of which is determined by the voltage applied to its armature by a D. C. generator. The voltage, and therefore the speed of the motor, is adjusted by a rheostat 31 operated by a motor 32.

As one feature of the invention means are provided for controlling this motor 32 and the various adjusting motors. This means includes a timer motor 33 which operates a plurality of

circuit closing cams

34, 35, 36, 37, 38 and 39 mounted on a shaft 48.

As another feature of the invention a differential 41 is positioned in the main drive shaft 42 from the motor 30 to the double facer 10 and the slitter-scorer 14, and this differential is provided with a motor 43 which when operated in one direction will cause the shaft section 42 leading to the double facer and the slitter-scorer to rotate slower than the portion between the differential and the main motor 30. Thus, when the required number of blanks of one size and shape has been made, the differential may be operated to slow down the double facer 10 preparatory to cutting a different size or shape of blank, and While the other units are being appropriately adjusted. At the time the operation of the differential begins the motor 21 is operated to give the knives 19 and one revolution to sever the web transversely at the delivery end of the double facer, but as hereinafter described, the slitter-scorer will maintain its previous speed. For this purpose there is provided an auxiliary motor which will maintain the speed of the blades so that they will advance the severed section and form a gap between the web and the severed section.

When the severed section has advanced in respect to the now slower running double facer to form a gap, and that gap has reached the slitter-scorer, the motor 27 of the latter is operated to swing one set of slitting or scoring blades out of position and another, which has had its blades adjusted for the next job, will swing into position preparatory to starting the next order for blanks which differ in some particulars from those of the preceding order.

The blades of the splitter-scorer 14 are normally driven from the section 42' of the main drive shaft which is beyond the differential 41, and through a chain 44 and gears 44', so as to have a peripheral speed equal to the linear speed of the web. As one feature of the invention means are provided for maintaining this rotational speed after the section 42' of the main shaft has been slowed down by the differential and the web has been cut in two, and so that the blades will act to advance the severed section while slitting and scoring it. For this purpose there is provided a motor 45 for driving the slitting and scoring blades through a chain 46, and with normal peripheral speed, so that the blades act on and also advance the severed section until the end of the latter has passed said blades. To permit this driving of the slitter-scorer at a faster speed than that of the shaft 42' after the latter has slowed down, there are provided two overrunning clutches 47 and 48, the clutch 47 being between the motor 45 and the gears 44 and the other clutch 48 being between the shaft 42' and gears 44. Thus the speed of the severed section is not changed when the shaft 42' slows down, because the motor 45 maintains the speed of the slitter-scorer blades and that of the severed section until after that section has passed said blades.

From the foregoing it will be seen that there are a plurality of motors which are intermittently operated to make the various adjustments. Before these adjustments are made the motor 21 is operated to sever the web at the discharge end of the double facer 10. Motor 43 then operates the differential to slow down the double facer. Motor 27 is then operated to swing one set of slitter-scorers out of position and another set into position, and motor 24 is operated to readjust the cut-off for longer or shorter box blanks.

In Fig. 5 there is illustrated a wiring diagram for the operation and timing of the various motors of the machine. In this specific embodiment D. C. current is supplied through the lines 50-51 for operating the reversible rheostat motor 32 and certain of the control units, and A. C. current is supplied through the lines 5253 for operating the cam driving motor 33 and various solenoids which effect the control of the operating parts of the machine. The motor 32 operates the movable element of the rhetostat 31 through a shaft 56, which to avoid confusion is diagrammatically illustrated in dotted lines. The rheostat motor 32 is directly connected to the line 50, and is connected to the line 51 through lines 54 and 55 which include the field coils 59 and 60 of the motor 32, and also include push buttons or switches 57 and 58 whereby the rheostat may be rotated in either direction to increase or decrease the speed of the machine.

The rheostat has three segments a, b, and c, which are wiped by a movable contact d operated by the motor 32. Segment a is connected to the line 55 including field coil 59 and segment 0 is connected to the line 54 containing field coil 60. By operating one or the other of the push buttons 57 or 58 the rheostat motor may be manually controlled to rotate in the desired direction to increase or decrease the speed of the motor 30. To permit bringing the speed to a predetermined one, the center segment 11 of the rheostat is connected by a line 61a to a solenoid 61 which operates a switch 62 in a line 63 leading to the timer motor 33 and to the circuit controlled by the cam 34.

When the motor 30 is slowed down, the movable contact member of engages segment b, the time delay relay coil 61 is energized, opening switch 62a, so that the relay coil 64 is no longer energized, and the switch 62 is closed to start the timer motor 33. When the circuit of coil 64 is opened it opens the circuit of the time delay relay coil 61, but this coil 61 maintains contact for a short delaying period before it drops out. By this time cam 34 has rotated far enough to close switch 34a, so that when switch 62 opens the motor 33 continues to run for the duration of the program cycle. When coil 61 is de-encrgized switch 62a recloses, but coil 64 remains de-energized because contact 68 has opened.

The

lines

50 and 51 of the direct current circuit are connected through a solenoid 64 and a push button 65 in parallel with the two

switches

67 and 68 which are energized by the solenoid 64 when the latter is energized by the closing of the push button 65. Thus the push button may be immediately released and the

switches

67 and 63 will be held closed until switch 62a is opened. The switch 68 closes the circuit through line 69 to the movable member d of the rheostat 31. The preset speed feature may be cut out of the circuit by a switch 70 movable to connect the

lines

50 and 51 through pilot light 51a.

When the switch 62 is closed by solenoid 61 current 7 'may flow from the line 53 through the motor 33,

lines

72 and 63, switch 62 and line 71 to the line 52, and the program switch control motor 33 will start rotation. This causes the cam 34 promptly to close the switch 34a which is in parallel with the switch 62 and the latter may open, but the circuit of the timer motor 33 will remain closed for one revolution, and until the cam 34 opens the circuit at 34a. The motor 33 also rotates the cams 35 to 39 which are set to close the circuits of the various adjusting motors, and in the proper sequence, and to hold them closed for the time required to make the necessary adjustments for the next order of blanks.

The cam 35 closes a switch 35a so that current may flow from line 53 through line 72 and a solenoid 73 to the line 52. This solenoid closes the circuit of the auxiliary motor 45 which drives the slitting and scoring blades of the slitter-scorer 14 through chain 46 at a peripheral speed of for instance 200 feet per minute, after the differential 41 has operated to slow down the shaft 42' which normally drives the blades. This driving of blades by either the shaft 42' or the motor 45 is permitted by the overrunning clutches 47 and 48.

In Figs. 4a, 4b and 4c the rotary heads of the rotary shear 13 are shown as viewed from the opposite side of Fig. 2. The cutter 19 or the shaft therefor has a cam 79 which operates to control the circuit of the motor 21 of the cutoff. Normally the cutter is at rest and in the position shown in Fig. 4a; the circuit of the motor 21 is open; and the sheet may pass freely between the blades.

When cam 36 closes the contacts 36a the rotary knives 19 and 20 make one revolution through successive positions shown in Figs. 4a, 4b and 40 to sever the web. Current is supplied through line 80, and the switches 77 and 77a are normally closed. When cam 36 closes switch 36a solenoid 75 is energized through line 74, cam operated switch 77 and line 76. The energized solenoid closes switches 78 and 78a. Switch 78 remains closed after switch 36a opens, so that the motor 21 of the cut-off 13, which has been started by the closing of switch 78a, continues its rotation. The solenoid 75 also opens switch 77a in the circuit of a solenoid 82.

Starting from the position shown in Fig. 4a the motor 21 rotates cutter heads 19 and 20 to the position shown in Fig. 4b, where the blades coact to sever the web. The heads continue to rotate to the position shown in Fig. 40, at which point cam 79 opens switch 77, thereby deenergizing solenoid 75, whereupon switches 78 and 78a open and switch 77a closes. The opening of switch 78a disconnects the motor 21 from the line, and the closing of switch 77a energizes solenoid 82 through plugging switch 83, which is closed when the motor 21 is running at full speed. The energizing of solenoid 82 closes contacts 81 which reverse the flow of current to the motor 21 until such time as the speed of motor 21 has dropped almost to the point at which it starts reverse rotation, at which time plugging switch 83 opens, leaving motor 21 at rest and stopping the cutting heads in the position shown in Fig. 4a. This plugging switch may be of the type shown in General Electric Co. Bulletin (IR-2962.

In parallel with the cam-operated switch 36a there is provided a push button switch 84 whereby if desired the shear motor may be operated independently of the control by the switch 36a, for instance to cut off an irregular end section.

As soon as the web is severed the cam 37 operates to close a switch 37a in a line 35 connecting

lines

52 and 53, and in this line is a solenoid 86 for closing the switch 87 in the circuit of the differential motor 43. The action of the differential is such that it opposes that of the main motor and slows down the double facer, for instance to a speed of 30 feet per minute, without slowing down the slitter-scorer, and thus forms a gap in the sheet, permits rotation of the frame of the slitter-scorer, and brings a different set of blades into operative position. As soon as the tail of the severed web passes the slitter, cam 35 stops the auxiliary motor 45. When this motor stops, the clutch 47 overruns and the drive shaft picks up the slitter drive through the overrunning clutch 48.

At the completion of one order the frame is rotated to move one set of blades out of operating position and another into position, the direction of rotation being dependent upon which of the sets of blades has been adjusted for the next order. Therefore the motor 27 for rotating the frame of the slitter-scorer is a reversible one.

The cam 33 controls the starting time of motor 27 which acts to bring into operating position the slitting and scoring blades which have been adjusted for the next batch of blanks. Current for the motor is supplied through line 89 and flows in either one direction or the other to the motor 27, depending on which of the switches 91 or 92 is closed. These switches are operated by solenoids 93 and 94, and current from line 53 may be directed to either solenoid by a pre-selector switch 95 in series with the switch 38a, which is operated by the cam 38. Either of the solenoids 93 and 94 may be momentarily closed by operating the push button switch 96 or the switch 96, so that in case the blade carrying frame does not stop in exactly the desired position it may be jogged along in the desired direction, and to the desired extent.

The cam 39 is for controlling the adjusting of the unit 15 which cuts the slitted and scored web into sections, each of the proper length corresponding to the periphery of the desired box. This unit may be of the same type as each of the units 12 and 13 in my patent 2,309,728, and has a reversible motor 24 corresponding to one of the motors 255 in Fig. 16 of said patent, for adjusting the frequency of operation of the cut-01f blades, and therefore the length of the blanks. There may be a second one of these units. In that case the wiring associated with cam 39 will be duplicated and controlled by an additional cam similar to cam 39.

The cam 39 at the proper time closes contacts 97 which permit current to flow from the line 53 through normally closed push button switch 98 and then through a switch 99 and the contacts 97 to a preselector switch 100. This may be positioned to direct the current from line to either the solenoid 101 or 102, and through line 100' to the line 52. These solenoids act to close either the switch 103 or 193 to actuate motor 24 in one direction or the other for adjustment as desired of the frequency of operation of knives which cut the strips into sections of the proper length for the box blank. The switch 99a corresponds to switch of the Behrens Patent 2,320,710, and is opened to stop the motor 24 when the preselected sheet length has been'reached.

When an order is completed the main motor 30 is at a speed corresponding to 200 feet per minute, and when the movable member of the rheostat is in the central position it closes the circuit of the coil 61 to close the switch 62 and start the motor 33. The switch 62 may immediately reopen, as the circuit of the motor will then be closed by the cam 34 as soon as the motor starts.

Preliminary to starting the continuous running feature and before the machine has been slowed down, the oporator makes the following preparation:

1. The cam-operated preselector switch 95 on the slitting and scoring attachment is set to the forward or reverse position, depending upon the direction in which the frame must be rotated to bring one or the other of the two idle pairs of shafts into position for the next order.

2. The cut-off preselector to switch 99a is set according to the sheet length desired for the next run, and the long-short selector switch 109 is set to the appropriate position.

3. The hand-automatic selector switch 99 on the cutoff is set to the automatic position.

4. The hand-automatic selector switch 70 on the master control panel is set to the automatic position. When this is done the pilot light 51a goes out, indicating that the setup is in readiness for the automatic cycle to begin.

The cycle is initiated by momentarily pushing the run button 65 which completes a circuit from line 51 through relay coil 64, switch 62a and selector switch 70 to the line 50. Energizing coil 64

causes contacts

67, 68 to close. The upper contact 67 parallels the push button 64, so that even though the push button is released the coil 64 remains energized.

From the foregoing it will be seen that the sequence of operations effected by the series of cams is as follows:

1. The main motor 30 is brought to that speed which will advance the web about 200 feet per minute, at which time the motor 45 of the slitter-scorer is at rest, the clutch 47 is overrunning, and the clutch 48 is driving the slitterscorer.

2. The cam 34 operates the switch 34a which holds the circuit of the motor 33 closed during one complete .revolution of the cams, so that the switch 62 may be reopened.

3. The cam 35 closes the circuit of the auxiliary motor 45 of the slitter-scorer.

4. The cam 36 then closes the circuit through the solenoid 75 which closes the switches 78 and 78a, whereupon the shear motor 21 at the delivery end of the double facer severs the web.

5. The cam 37 then closes the circuit of the motor 43 and starts the differential, which slows down the double facer to about 30 feet per minute, but the motor 45 continues to drive the slitter-scorer at about 200 feet per minute to slit the section which has been cut off.

6. When the end of the severed section passes the slitter the cam 35 opens the circuit of the auxiliary motor 45, and the clutch 48 acts to drive the slitter-scorer at about 30 feet per minute.

7. The cam 38 then operates to close the circuit of the motor 27, and the frame of the slitter-scorer is rotated in one direction or the other, depending upon the setting of the switch 95, and to bring into position the set of blades which have been adjusted for the next order.

8. The cam 39 then closes to operate the motor 24 in one direction or the other to operate the cut-oh? more or less frequently, as shorter or longer sheets may be required.

9. The cam 37 then opens contacts 37a to stop the differential motor.

10. The cam 34 then operates to open the circuit of the motor 33, and the latter will remain at rest until the order for one type of blanks has been completed and the main motor has been slowed down, and the switch 62 is again closed.

For adjusting the machine to cut longer sheets the switch 100 is in the position shown in Fig. 5, and the adjusting motor 24 will rotate in one direction. For adjusting the machine to cut shorter sheets the switch Hit) is moved to the opposite position, and the solenoid 102 will be energized to close the switch 163' to rotate the adjusting motor 24 in the opposite direction.

If it is desired to make adjustments by hand the switch 99 is moved to the right to cut the contact 9'7 out of circuit and bring the push button switch 104 into the circuit. Thus, by moving the switch 100 to the right or to the left and momentarily depressing push button 164, either switch 103 or 103 may be momentarily closed. This entire control may be cut out by opening push button switch 98.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a machine comprising feed mechanism for continuously longitudinally advancing strip material and a second mechanism relatively spaced from the feed mechanism along the path of travel of said material and operative upon the latter, said second mechanism comprising a plurality of operating heads and means for selectively shifting said heads into operative position with respect to said strip, a cut-off means for said strip in proximity to said feed mechanism and between the latter and the said second mechanism and operative independently to sever the said strip, a common drive shaft for said mechanisms, auxiliary drive means for the second mechanism and means for actuating said auxiliary means to operate said mechanism independently of the common drive shaft and at a rate of speed corresponding to the normal operating speed of the common drive shaft, means for reducing the speed of said common drive shaft, and means for automatic coordinated operation of said cut-off means, auxiliary drive means, the said head-shifting means, and the means for reducing the speed of the drive shaft, to cut off the web, to simultaneously actuate the means for reducing the speed of the drive shaft and to initiate operation of said auxiliary drive means so as to reduce the speed of the feed mechanism while maintaining the relatively high operating speed of the second mechanism, to subsequently interrupt the operation of the auxiliary drive means after the cut ends of web have been separated by the differential speeds of the feed mechanism and second mechanisms to a required extent so as to reduce the operating speed of the second mechanism to the reduced speed of the drive shaft, to thereafter actuate the said headshifting means to bring a selected operating head into operative position between said cut ends of web, and to interrupt the operation of the shaft speed reducing means so as to restore the operating speed of the shaft and the said mechanisms.

2. A machine for making box blanks including a double facer for making and continuously delivering a web of stiff sheet material, web cut-ofif means at the delivery end of said double facer and independent motor means for operating said cut-off means, a unit for slitting and scoring the advancing web, said unit comprising a plurality of slitting and scoring heads operative individually on said web and motor means for shifting said heads selectively into the operative position, a common drive shaft for the double facer and said slitter-scorer unit, a main drive motor for said shaft, means for operatively connecting the double facer and the slitter-scorer unit individually to said shaft, the means for connecting the slitter-scorer unit to the shaft comprising overrunning clutch means providing for operation of the said unit by auxiliary drive means independently of and at speeds corresponding to the normal operating speed of said common shaft, auxiliary drive means connected to the slitter-scorer unit, means including a differential gear unit interposed between the said drive shaft and the main drive motor and separate motor means for driving said differential to reduce the speed of the shaft independently of the main drive motor, and means for automatic coordinated operation of said cut-off means, differential unit, auxiliary drive means, and head-shifting means, to cut off the web, to simultaneously actuate the differential unit and the auxiliary drive means to reduce the speed of the drive shaft and of the double facer while maintaining the relatively high operating speed of the slitting and scoring unit, to subsequently interrupt the operation of the auxiliary drive means after the cut ends of web have been separated to a required extent so as to reduce the operat ing speed of the slitting and scoring unit to the reduced speed of the drive shaft, to thereafter actuate the said head-shifting motor means so as to bring a selected slitting and scoring head into operative position between said out ends of web, and to interrupt the operation of the differential unit so as to restore the operating speeds of the double facer and the slitting and scoring units.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Laabs Mar. 20, 1934 Fairchild Aug. 21, 1934 5 Gulliksen Aug. 11, 1936 Pecker May 18, 1937