US2214488A - Knife - Google Patents

Description

10, '-1. STERN :1- AL KNIFE 011 Filed. June 25, 1935 2 Sheets-Sheet 1 INVENTORi Y mzwb b,

ATTORNEYS 1 pt. 19,1940. 4 am-RN Y 2,214,488

mms- 7 Original Filed June. 25, 1935 2 Shaets-$heet 2 IN VENT OR? ATTORNEY5 Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE KNIFE Original application June 25, 1935, Serial No.

28,296, now Patent No. 2,146,274, dated February 7, 1939.

Divided and this application February 7, 1939, Serial No. 255,010

8 Claims.

This application, which is a division of Patent No. 2,146,274, granted February 7, '1939, r lates to novel apparatus for and methods of cutting fibrouspaper boards and more particularly, relates to novel apparatus for and methods of operating knives continuously for cutting varying lengths of fibrous boards.

In the manufacture of fibrous paper material, the paper after it has passed'through the corrugating machine and been formed into corrugated board, emerges as a continuous web which is fed to cutting knives at a rate of-speed determinedby the rate of operation of the machine.

The strip material of the web is then cut into predetermined lengths by the knives which are usually operated in a cycle whose time varies in accordance with the size of cut desired.

The operation of the knives may be broadly divided into two classifications, one, the intermittent operation and, two, the continuous operation.

In the case of the intermittent operation of the knives, either a timing device or a target is provided. The target is engaged by the end of the paper being fed past the knife so that when a predetermined length ofpaper has been fed past the knives, the forward edge of the paper engages the target which in turn operates to cause an engagement of a clutch through which a driving shaft drives the drum carrying the knife.

The knife drum which up to thispoint hasbeen stationary now starts its cycle of operation, rotating to a point where theknife engages and cuts the paper and thereafter continues the l atation until the cutting operation has been completed and the drum with the knife thereon has returned to the original stop position at which point the clutch disengages the drum from the driving shaft. A cycle hasthus been completed and the drum is prepared for the second cycle when the new edge of the strip material engages the target to again close the clutch.

In this type of operation, due consideration has to be given to the time from the.instant when the edge of the paper engaged the target to the beginning of the out which obviously takes place some time later. In this interval, there is (Cl. 164-68) v driving shaft speed soon begins to wear so that the time interval between the operation of the target and the engagement of the knife with the paper varies depending upon the slip of the clutch. This results in an error in the size of the paper'cut of as much as a quarter of an inch which becomes a very serious factor when a large number of cut sheet material is involved, not only in the loss of paper but also in the extra trimming operation involved.

The second principle referred to above involves a construction in which the drums carrying the knives are rotated at a continuous speed and at a predetermined position in the cycle of the drum the knives engage the paper to perform the cutting operation.

For different size cuts, provision is made for changing the speed of the knife carrying drum either to a greater or lesser speed depending upon whether a smaller or larger cut size is desired.

During thecutting interval, the knife engages the paper and accordingly must move forwardly with the paperat the same rate of speed as the paper, if it isto avoid either the tearing or buckling of the paper during cutting. While this is a comparatively simple problem for a single time cycle of the cutting knives, the problem is rendered more difficult where the cycle time is changed for different sized cuts.

Heretofore the only solutions proposed for obtaining a synchronous or equal rate of speed of movement of the knives and the paper at the instant of cutting have been based on principles involving complex mechanism and providing only an approximate synchronism.

Thus in the patent to Swift No. 917,503, no detailed solution for this difliculty is suggested. In the patent to Sieg No. 1,897 ,867, it is proposed to follow the principles outlined in the patent to Harbrecht, No. 1,039,124 by using elliptical gears for driving the knife carrying drums. By reason of these elliptical gear drives, the knife carrying drum is gradually increased from a minimum speed at the beginning of a cycle up to a speed at which the drum is rotating at the speed of the corrugated paper web. At this point the knife engages the paper for cutting operation. At the end of the cutting operation, the drum through the action of the elliptical gears again reduces its speed to the original minimum speed.

In order to change the size of cuts, the time consumed for this cycle is changed as described above. Inasmuch, however, as with the change in time cycle of operation, the knife at the point in the elliptical gear previously described will no longer operate at the same speed as the paper moves, it is necessary to move the relative position of the knife with respect to the elliptical gear to that position of the elliptical gear which at the new time cycle rate, moves at the same speed as the paper.

However, both Harbrecht and Sieg make a fundamental erroneous assumption. An elliptical gear, by definition, is one whose speed is continuously changing. While it is possible to obtain an approximation'of uniform speed for cutting at one position of the elliptical gear where it is most nearly circular so that the knives will move at the same speed as the paper throughout the cutting period, this is not possible at a variety of positions of the elliptical gears. Accordingly, when either Harbrecht or Sieg shift the position of the knife with respect to the elliptical gears there results inevitably a non-synchronous condition between the speed of the paper and the speed of the knife at least during a portion of the cutting period.

Thus in both Sieg and Harbrecht, two adjustments are made, namely, one which involves a change in the time cycle of the knife and the other involving a compensation for this change in time cycle by a change in the relative position of the knives and the elliptical gears, the distinction between Harbrecht and Sieg being that in Harbrecht the cutting machine must be brought to a stop for adjusting the elliptical gears with respect to the knives whereas in Sieg this can be done with the machine in operation. In both cases, however, a fundamental fallacy in principle of operation exists.

In accordance with our invention, we contemplate a construction of knives and the operation thereof in which no compensating adjustment of the elliptical gears is necessary or provided. The drum carrying knives are in a fixed and rigid position with respect to the elliptical gear exactly as is obtained in Harbrecht before any adjustment thereof is attempted. The only adjustment is the time cycle adjustment as in Harbrecht, but no change in the relative positions of the drum with respect to the knife is made; instead, as pointed out above, this is maintained rigidly fixed so that that portion of the elliptical gear which is either accurately or approximately circular may be employed for the cutting interval to maintain the knives moving in synchronism with the speed of the paper.

This condition for every time cycle variation is obtained by merely using more or less of the elliptical gear for driving the knife drums.

In accordance with our invention, we drive the knife drums from two sources; first, from a Reeves drive directly through circular gears whose time interval is changed for obtaining different sized cuts. A second drive for the knife drums is obtained through a pair of elliptical gears which are normally non-operative while the cutting cycle is being determined.

At a predetermined point in the cycle, the elliptical gears become effective to increase the speed of the knife drums to the cutting speed, at which point the knives move at the same speed as the paper. Thereafter, the knives are decelerated by the elliptical gears until they reach the speed at which the circular gears again drive the knife drums for repeating the cycle.

Thus, as will be more clear from the description to follow, we have made a radical departure both in the principle of operation and the construction. Instead of adjusting elliptical gears which requires complicated mechanism and in the end is inaccurate, we make no adjustment whatsoever on the elliptical gear adjustment but instead provide multiple drives, a principle never heretofore used in this mechanism. The multiple drive in which the function of the timing of the cycle is assigned to one drive and the synchronizing to the other drive is far simpler than any other system, requiring practically little or no additional parts. At the same time it is far more accurate in operation.

Accordingly, an object of our invention is to provide a novel construction of knives for strip material in which two separate drives in parallel relation to each other are provided for the knife drums, one drive determining the time cycle and the other for bringing the knife to the synchronous speed.

Still another object of our invention is to provide knife drums for continuous strip material in which a fixed relation is maintained between the knife drum'and the elliptical gears.

Still a further object of our invention is to provide novel apparatus for and methods of cutting strip material in which it Is necessary to change the time cycle only and no compensating adjustments of elliptical gears are required.

There are other objects of our invention which together with the foregoing will appear in the detailed description which is to follow in connection with the drawings.

Figure l is a schematic illustration of one form of our invention.

Figure 2 is a schematic illustration of a modified form of our invention.

In Figure 1 We have illustrated a form of our invention in which we have eliminated the clutch mechanism I1 and 4| of Figure 1 in the parent case. the Reeves is obtained as in the modification of the parent application. This Reeves drive I2 consists of drive cone pulley I3 and driven cone pulley I4; attached to pulley I4 is the shaft II connected to drive feed rolls 38 and to drive other devices hereinafter specified. Secured to shaft I6, however, and rotatable therewith is a mutilated gear I03 which has teeth only about a portion of the circumference, this portion being that part of each cycle during which the knives 28 and 34 are to be driven at a predetermined'speed in accordance with the size of cuts to be made. In the multiple drive connection, shaft II is connected through the pulleys I00 and IOI for driving gear I02 meshing the mutilated gear I03. Gear I03 like gear I03 has teeth about only a portion of its circumference, namely, that portion in the cycle during which the knives 28 and 34 are to be accelerated and decelerated from a speed below cutting speed up to the cutting speed and then back to the original speed.

In normal operation, the gear I03 meshing with the drum gear I04 will drive the knives 20 and 34 at a predetermined speed determined by the Reeves drive I2. This rate of speed during the period while gear I03 meshes with gear I04 determines the size of the cut sheets. A third mutilated gear I03" meshing with gear I04 provides a third multiple drive for the knives 34 and 28. v

In operation, at the beginning of the cycle gear I03 drives the knives as described above during that portion of the cycle when the speed of the drum is maintained constant and determined by the Reeves drive I2 as explained above. At the end of this interval, the teeth of gear I03 The same drive and speed control through 2.a14,4ss I are about to disengage from the teeth or gear I 04. At the instant that the last tooth of gear I03 passes from'engagement with gear I04, the first tooth of gear I03 which up to this point has been driven through the gear chain including the elliptical gears, engages with the tooth of gear From this point on in the cycle, driving power is supplied through gears I02, I03 which through gears I05 and I06 drive the elliptical gears I01 and I08. As the gears rotate, the gear ratio between the gears I01 and I08 gradually undergo a change in the manner described in detail above as the small part of gear I01 meshes with the large part of gear I08 until a one to four ratio is obtained. At this time the knives 34 and 28 are rotating at their maximum speed at which point they are rotating at approximately the speed of the paper. 3

Just before the knives engage the paper for cutting, gear I03 for a short interval disengages from gear I02 while gear I03" driven by driving belt I00 through pulley IOI meshes with gear I04. During this latter interval, while these circular gears are in mesh, the knives start their cutting operation. During this period, the knives are being driven by the circular gears and at a fixed and invariable speed which is always the same as the speed of the paper.

At the end of the. cutting interval, gear I 03" disengages gear I04 while gear I03 again meshes with gear I02 and as the elliptical gears continue to rotate, the gear ratio between gears I01 and I08 gradually undergoes a change until knives 34 are again rotating at their minimum speed. At this speed the first tooth of gear I03 again meshes with a tooth of gear I04 to repeat the above described cycle.

Inasmuch as the speeds of gears I03, I03 and I03" are predictable, their teeth may be so cut that they will invariably properly mesh with their corresponding gears as they come 'into meshing contact. However, we recognize that this may create a problem and there are, therefore, certain advantages in employing the power transmission systems utilizing the clutch described in our second modification.

To overcome the problem of these gear structures, we have provided a modification shown in Figure 2. in which the mutilated gear I09 driven through the Reeves drive I 2, in turn drives the gears which drive the knives 28 and 34. I

During the interval while the teeth of gear I09 are in meshing relation with their corresponding gear teeth, the knives 28 and 34 are driven at a constant speed which determines the size of the cuts of the material. Although this is the minimum speed of the knives 28 and 34, the gear ratio between the gears H0 and I II is such that the shaft II2 rotates at a faster speed than the driver of clutch 4I. Accordingly, clutch 4I rides.

freely and does not transmit any driving power.

When, however, the last tooth of gear I09 passes from engagement with the tooth of the gear driving the knife 28, the driver of clutch 4| becomes efiective and by rotating shaft II2 drives the elliptical gears I I0 and I I I. During this portion of the cycle, the gear ratio between gears III] and I II increases in the manner described above, accelerating the knives until they reach the speed of the paper. During this interval the knives engage and begin to cut the paper. As in the previous case, the elliptical gears are made as nearly as possible circular so that during the cutting interval, the knives are operated at a constant speed equal to the speed of the paper. At the end of the cutting interval and as the drums continue to rotate, they are decelerated due to the reverse change in speed ratio of elliptical gears H0 and III.

When the drums have been decelerated to the original speed, the first toothed gear I09 meshes with the tooth of the drum gear and the above described cycle is repeated. In this case, inasmuch as the time interval from the instant when the last tooth of gear I09 passes out of engagement with the drum gear to the instant when the first tooth again engages in a constant and predictable interval, the gear teeth of gear I09 can be designed so that they'will always mesh with the drum gear although in this case also the first modification is found preferable because of simpler design problems.

Although we have not shown or described any of the details of the knife construction, it will be obvious that we may use any of the well-known arrangements of knives. It will beclear to those skilled in the art that the drums carrying the knives are mounted at a slight angle with respect to the direction of movement of the paper so as to produce straight cuts and that the knives themselves are so curved as to provide straight cuts.

Although for purposes of illustration we have chosen to illustrate our invention mainly as applied to knives mounted on drums, it will be obvious to those skilled in the art that we may employ other well known constructions of knives.

Moreover, although the invention is described specifically as applied to knives for cutting corrugated board, it will be clear that it may be applied to knives for cutting any other materialclear, in dividing the time of a cycle into four dis tinct periods, one, the period when synchronism is desired, two, the decelerating period, three, the period which controls the time of the cycle, and four, the accelerating period and in so arranging the mechanism for carrying this out. such as the elliptical gear here used for purposes of illustration, that the only variable is the mechanism which controls the time of the cycle in third period so that no changes of any kind are necessary in the elliptical gears or their equivalent.

By thus providing only one adjustment, the accelerating period, the decelerating period and what is of greatest importance, the cutting period, all remain at a fixed value consuming an in variable fixed interval of time.

Not only are we thus able to provide more accu-' rate cuts than have heretofore been possible, but our mechanism is greatly simplified and is made relatively inexpensive.

In illustrating our invention, we have not shown any of the details of the corrugators but have merely schematically illustrated feed rolls which determine the speed of the paper being fed to the knives and with which speed the wives must be maintained in synchronism during cutting. This speed is determined by driving the speed rolls from the same source of power described above, which drives the knives.

We claim:

1. In a device for cutting strip material, knife cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a positive drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle.

2. In a device for cutting strip material, knife cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a positive drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle and for rendering said first path ineffective in the intervals between the cutting cycle.

3. In a device for cutting strip material, knife 7 cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a gear drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle and for rendering said first path ineffective in the intervals between the cutting cycle.

4. In a device for cutting strip material, knife cutting means; means for-feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a great drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path including an overrunning clutch for transmitting power from said source of power to said knife cutting means for accelerating v and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle and for rendering said first path ineffective in the intervals between the cutting cycle.

5. In a device for cutting strip material, knife cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a positive drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle and for rendering said first path ineffective in the intervals between the cutting cycle; said positive drive including sectional gear.

6. In a device for cutting strip material, knife cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a positive drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle and for rendering said first path ineffective in the intervals between the cutting cycle; each of said transmission paths including sectional gears.

7. In a device for cutting strip material, knife cutting means; means for feeding the strip material to be cut at a constant speed past the knife cutting means; a source of power; a positive drive power transmission path from said source of power to said knife cutting means for operating said knife cutting means at a predetermined speed; a power transmission path from said source of power to said knife cutting means for accelerating and decelerating said knife cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle; each of said paths including sectional gears.

8. In a device for-cutting strip material, cutting means; means for feeding the strip material to be cut past the cutting means; a source of power; a first power transmission path from said source of power to said cutting means for operating said cutting means; a power transmission path from said source of power to said cutting means for accelerating and decelerating said cutting means; and means forming a part of said transmission path for rendering said second mentioned power transmission path ineffective during the cutting cycle.

ISAAC STERN.

BENJAMIN SKOLNIKOFF. JUVENTINO JOSEPH PESQUEIRA. SAMUEL OS'IROLENK.

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